Newtons Law Part 2
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Questions and Answers

What is the primary effect of a deeper counter jump on vertical jumping performance?

  • It decreases the overall energy output required for jumping.
  • It leads to a decrease in the time spent in the air.
  • It increases the force exerted on the ground immediately.
  • It increases the contact time with the ground, enhancing momentum. (correct)

How does longer landing time through a deep squat contribute to injury prevention?

  • It distributes the force evenly across the lower body.
  • It minimizes the total distance to reach the ground.
  • It allows for a quicker recovery time after landing.
  • It applies a smaller force over a longer period of time. (correct)

What is the result of performing isometric muscle contractions in terms of mechanical work?

  • Zero work is performed. (correct)
  • Variable work depending on muscle mass.
  • Positive work is performed.
  • Negative work is performed.

Which phase of the pitch process converts potential energy into kinetic energy?

<p>Cocking phase. (B)</p> Signup and view all the answers

What is the effect of force and displacement being in opposite directions on work performed?

<p>It results in negative work performed. (D)</p> Signup and view all the answers

How does a gymnast maximize their kinetic energy during a vault?

<p>By running as fast as possible during their approach. (A)</p> Signup and view all the answers

What role does elastic energy play in a gymnast's vault after foot planting on the springboard?

<p>It is stored temporarily until the board is released. (C)</p> Signup and view all the answers

What happens during the acceleration phase of a pitch as the pitcher prepares to throw?

<p>The kinetic energy is at its peak. (A)</p> Signup and view all the answers

What is the formula for the force of friction based on the coefficient of friction and normal force?

<p>$F_{friction} = μ * F_{normal}$ (A)</p> Signup and view all the answers

Which condition leads to the box beginning to slip when pushed?

<p>$F_{push} &gt; F_{friction}$ (D)</p> Signup and view all the answers

What does the symbol Σ generally represent in equations of motion?

<p>The total or net force in a given direction (C)</p> Signup and view all the answers

When analyzing forces acting on a stationary box, which statement is correct?

<p>Normal force is equal to the gravitational force acting on the box. (B)</p> Signup and view all the answers

If the coefficient of friction (μ) is increased, what effect does it have on the force of friction?

<p>The force of friction increases proportionally. (D)</p> Signup and view all the answers

What is the relationship between normal force (FNormal) and gravitational force (Fg) for an object at rest on a horizontal surface?

<p>FNormal = Fg (B)</p> Signup and view all the answers

Which of the following statements about tipping and slipping is true?

<p>Tipping occurs when the center of mass shifts too far outside the base. (A)</p> Signup and view all the answers

How can one calculate the normal force acting on an object resting on a scale at an angle?

<p>FNormal = Fg * cos(θ) (D)</p> Signup and view all the answers

What is the result when positive work is done on an object?

<p>The object's energy increases. (C)</p> Signup and view all the answers

How is power defined in the context of work and energy?

<p>The work done divided by the time taken. (A)</p> Signup and view all the answers

If a 0.2 kg baseball is stopped over a distance of 0.125 m from a speed of 22 m/s, what is the nature of work done on the baseball?

<p>The work is negative, decreasing the kinetic energy. (D)</p> Signup and view all the answers

What happens to a diver's potential energy when they drop from 10 m to 5 m above the water?

<p>It decreases. (C)</p> Signup and view all the answers

In the formula for power, which variables are essential for its calculation when moving an object at a constant velocity?

<p>Force and velocity. (D)</p> Signup and view all the answers

What is the likely consequence of friction acting on a moving box on a sticky floor?

<p>Work is negative, decreasing kinetic energy. (B)</p> Signup and view all the answers

If a gymnast applies a force to vault, how does this relate to energy transfer?

<p>The energy is transferred from the ground to the gymnast. (C)</p> Signup and view all the answers

How does the physics of energy transfer apply to a pitcher throwing a baseball?

<p>Work is done through acceleration of the arm. (A)</p> Signup and view all the answers

How does the ability to exert more power affect the speed of lifting weights?

<p>More power enables weights to be lifted quickly. (A)</p> Signup and view all the answers

Which factor contributes to a box being more stable and harder to tip over?

<p>Adding weight to the box. (A)</p> Signup and view all the answers

What effect does following through on a golf drive have on the ball's momentum?

<p>It extends the time the force is applied, increasing impulse. (D)</p> Signup and view all the answers

How does a soft landing technique affect the forces experienced during a landing?

<p>It dissipates force over a longer time, resulting in lower impact force. (D)</p> Signup and view all the answers

What is the relationship between the coefficient of friction and the likelihood of an object sliding?

<p>Pushing harder than the frictional force causes sliding. (A)</p> Signup and view all the answers

What is the calculated force experienced by a 50 kg gymnast landing hard over 0.20 seconds?

<p>937.5 N (B)</p> Signup and view all the answers

If a person has reduced power, how might this impact their ability to cross the street?

<p>They may need more time to cross due to slower movements. (A)</p> Signup and view all the answers

Which condition leads to tipping of an object rather than sliding?

<p>Pushing high up when the base is wide. (B)</p> Signup and view all the answers

What is the primary goal of force composition?

<p>To determine the net effect of combined forces. (A)</p> Signup and view all the answers

Which method uses a tip-to-tail approach for combining non-parallel forces?

<p>Polygon Method (D)</p> Signup and view all the answers

If a force is resolved into components, which of the following represents the stated method?

<p>Replacing a force with its components while maintaining the total effect. (D)</p> Signup and view all the answers

When drawing a free body diagram, which of the following steps does NOT belong?

<p>Measure the acceleration of the body. (A)</p> Signup and view all the answers

What is the significance of the moment arm when considering forces?

<p>It impacts the torque produced by the force. (C)</p> Signup and view all the answers

Which of the following describes the X and Y components of a force?

<p>One can be zero while the other is not. (A)</p> Signup and view all the answers

In the context of free body diagrams, what does the statement Σ = 0 imply?

<p>The object is in static equilibrium. (B)</p> Signup and view all the answers

If a ballerina's lower leg has a weight of 30 N and a moment arm of 0.50 m, what is the importance of this moment arm for her movements?

<p>It affects the effectiveness of the leg's propulsion. (A)</p> Signup and view all the answers

What is the potential energy of a 60kg diver at a height of 5m above the water?

<p>2940 J (D)</p> Signup and view all the answers

When the diver enters the water at 0m, what is the kinetic energy just before entry?

<p>5880 J (A)</p> Signup and view all the answers

What is the average force required to stop a 0.2 kg baseball moving at 22 m/s over a distance of 0.25 m?

<p>193.6 N (B)</p> Signup and view all the answers

What is the work performed on the diver if the water slows him down by 50% upon entry?

<p>4410 J (C)</p> Signup and view all the answers

How much kinetic energy does the baseball have before being stopped by the player?

<p>48.4 J (B)</p> Signup and view all the answers

What is the relation between power and work when lifting a 100 kg weight to a height of 2 m in 5 seconds?

<p>Power is calculated as total work divided by time. (D)</p> Signup and view all the answers

What would be the average force required to stop the same baseball over a distance of 0.125 m?

<p>387.2 N (A)</p> Signup and view all the answers

How does the recoil phase in the muscle-tendon unit affect the throwing motion?

<p>It stores energy to be released during the throw. (B)</p> Signup and view all the answers

Flashcards

Composition of Forces

Combining two or more forces to determine their net effect.

Composition of Non-Parallel Forces

Two or more forces acting on an object at the same time, creating a combined force.

Polygon Method

A method of finding the resultant force by drawing vectors tip to tail.

Parallelogram Method

A method of finding the resultant force by drawing vectors from the same point, forming a parallelogram.

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Resolution of Forces

Replacing a single force with two or more components, whose combined effect equals the original force.

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Free Body Diagram

A visual representation of all forces acting on a body, including internal and external forces, joint reaction forces, and the body's weight.

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What is energy?

The ability to do work.

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Joint Reaction Force

The force exerted by a joint on the bones it connects, balancing other forces to maintain stability.

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What is energy?

The ability to do work.

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Equations of Motion

Equations used to describe the motion of a body based on the forces acting on it.

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What is the Law of Conservation of Energy?

Energy can be transferred from one object to another or transformed from one form to another.

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What is potential energy?

The energy stored in an object due to its position or state.

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What is kinetic energy?

The energy possessed by an object due to its motion.

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What is work?

The transfer of energy by a force acting over a distance.

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What is power?

The rate at which work is done or energy is transferred.

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What is force?

The amount of energy needed to move an object a certain distance.

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Power

The rate at which work is done, or the amount of energy transferred per unit of time.

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Stability

The ability to resist tipping over, determined by the width of the base and the position of the applied force.

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Friction

The force that opposes motion between two surfaces in contact. It is determined by the coefficient of friction (μ) and the normal force (mg).

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Impulse

The product of the force applied to an object and the time for which it acts.

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Momentum

The measure of an object's motion, defined as mass times velocity.

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Impulse-Momentum Principle

The principle stating that the change in momentum of an object is equal to the impulse applied to it.

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Soft Landing

The technique used to reduce the forces experienced during an impact by increasing the time over which the force is applied.

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Impulse-Momentum Principle Application

The technique used to reduce the forces experienced during an impact by increasing the time over which the force is applied. Examples of applications include airbags in cars or landing mats for gymnasts.

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Mechanical Work

The product of the force applied to an object and the displacement of the object in the direction of the force.

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Positive Work

Work done when the force and displacement are in the same direction.

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Negative Work

Work done when the force and displacement are in opposite directions.

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Isometric Muscle Contraction Work

No work is done during an isometric muscle contraction because there is no change in muscle length.

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Eccentric Muscle Contraction Work

Work done during a lengthening muscle contraction.

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Concentric Muscle Contraction Work

Work done during a shortening muscle contraction.

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Energy

The ability to do work.

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Kinetic Energy

The energy of motion.

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Elastic Energy in Muscles

The ability of a material to store energy when stretched or compressed and release that energy upon returning to its original shape.

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Recoil Phase

The phase of movement where the stored elastic energy is released, contributing to the force of the movement.

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Potential Energy (PE)

The energy an object possesses due to its position or height relative to a reference point.

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Kinetic Energy (KE)

The energy an object possesses due to its motion.

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Work

The amount of energy transferred when a force is applied over a distance.

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Force to Stop an Object

The force required to stop a moving object.

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Work-Energy Theorem

The relationship between force, distance, and work. Work equals force multiplied by distance.

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Coefficient of friction (μ)

A measure of how sticky a surface is, determining the force needed to initiate motion between two surfaces in contact.

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Normal force (FNormal)

The force perpendicular to the surface of contact between two objects. It's equal to the object's weight when the object is on a horizontal surface.

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Force of friction (Ffriction)

The force of friction is directly proportional to the normal force and the coefficient of friction. It always acts in the opposite direction to the motion.

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Slipping force

The state where an object begins to move across a surface when the applied force exceeds the maximum static friction force.

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Tipping force

The state where an object rotates around a fixed point when the applied force creates a larger torque than the opposing torque.

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Net force (ΣF)

The sum of all forces acting on an object in a particular direction. For an object at rest or moving at constant velocity, the net force is zero.

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Inertia

The tendency of an object to resist changes in its motion. It's directly proportional to an object's mass.

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Study Notes

Newton's Laws

  • Newton's laws describe how forces act on objects
  • Combining two or more forces determines the net effect.
  • Linear forces are added (if in line) or subtracted (if opposite direction)

Composition and Resolution of Forces

  • Composition is combining two or more forces to find the net effect
  • Resolution is replacing a single force with two or more. components
    • Usually resolved into vertical (Fy) and horizontal (Fx) components
    • For any force (F)
      • X-component (Fx)
      • Y-component (Fy) -Sometimes one of these (Fx or Fy) may be zero

Free Body Diagrams

  • Steps to draw a Free Body Diagram:
    1. Identify and isolate the free body.
    2. Establish a coordinate reference frame.
    3. Draw all forces (internal and external) on the body.
    4. Draw the joint reaction force.
    5. Write the governing equations of motion (ΣFx = 0; ΣFy = 0; Σ = 0)).

Tipping vs. Slipping

  • Friction: A force that opposes motion between surfaces
    • Coefficient of friction (μ) describes how "sticky" a surface is
    • Friction force = μ * Normal Force
  • Box tipping
    • If push force is greater than friction, the object will begin to slide
    • If push force is greater than the torque created by gravity, the object will begin to tip

Impulse-Momentum

  • Momentum (M): The quantity of motion possessed by an object
  • M = m * v (mass x velocity).
  • Impulse: The quantity of net force applied over a period of time Impulse = ΣF * t 
  • The impulse applied to an object is equal to the change in momentum.
  • Impulse–momentum relationship  ΣF * t = Δmv

Work, Energy, Power

  • Work: The product of force and the displacement in the direction of the force.
    • Work = Force * distance
  • Energy: The capacity to do work.
  • Kinetic Energy: Energy of motion (KE = 1/2mv²)
  • Potential Energy: Energy due to position (PE = mgh)
  • Elastic Energy: Energy due to deformation (EE = 1/2kx²)
  • Power: The rate at which work is done or energy is transferred.
    • Power = Work / time

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Newtons Laws Session 2 POST - Part 2 PDF

Description

This quiz covers Newton's Laws of motion and the principles of composition and resolution of forces. Learn about free body diagrams, how to isolate forces, and the concepts of tipping versus slipping. Test your understanding of these fundamental physics concepts.

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