Physics of Forces and Momentum

Questions and Answers

What was the significance of Galileo Galilei and Isaac Newton's contributions to understanding motion?

They introduced the concept of friction in motion

They proved that force cannot change the shape of an object

They developed a new way to measure the velocity of an object

They developed an entirely different approach to understanding motion (correct)

What can a force be used to change in an object?

Its colour and texture

Its magnitude of velocity or direction of motion (correct)

Only its direction of motion

Only its shape and size

What is the main reason why a spring expands when a force is applied to it?

The force causes the spring to vibrate

The force applies a pressure on the spring

The force increases the temperature of the spring

The force changes the shape of the spring molecules (correct)

What happens when a small force is applied to a box on a rough surface?

The box does not move due to friction Signup and view all the answers

What type of force is responsible for changing the shape of a rubber ball when hit with a hockey stick?

Contact force Signup and view all the answers

What is the primary function of the strings X and Y in Fig. 8.3?

To balance the forces acting on the block Signup and view all the answers

What happens when a force is applied to an object in a direction opposite to its motion?

The object decelerates Signup and view all the answers

What is the result of a force acting on an object in contact with a rough surface?

The object experiences friction Signup and view all the answers

What is the primary reason why the block does not move in Fig. 8.4(b)?

The friction force is greater than the pushing force. Signup and view all the answers

What happens when the pushing force is greater than the friction force in Fig. 8.4(c)?

The block starts moving in the direction of the pushing force. Signup and view all the answers

What is the result of applying balanced forces to an object?

The object remains stationary. Signup and view all the answers

What happens when an unbalanced force acts on an object?

The object moves in the direction of the greater force. Signup and view all the answers

Why does the bicycle slow down when we stop pedaling?

Due to the friction force acting opposite to the direction of motion. Signup and view all the answers

What is necessary to maintain the motion of a bicycle?

A continuous application of an unbalanced force. Signup and view all the answers

What is the relationship between the pushing force and the friction force in Fig. 8.4(b)?

The pushing force is equal to the friction force. Signup and view all the answers

What occurs when two opposite forces of different magnitudes pull the block?

The block moves in the direction of the greater force. Signup and view all the answers

What was Galileo's father's desire for his son's career?

A medical doctor Signup and view all the answers

What was the title of Galileo's first scientific book?

The Little Balance Signup and view all the answers

What is the reason why we tend to fall backwards when a bus starts moving suddenly?

The inertia of our body Signup and view all the answers

What is the underlying principle behind the phenomenon of being thrown to one side when a motorcar makes a sharp turn at high speed?

The law of inertia Signup and view all the answers

What is the result of an unbalanced force being applied to change the direction of motion of a motorcar?

The passengers are thrown to one side Signup and view all the answers

What is the primary reason why Galileo did not complete his medical degree at the University of Pisa?

He was more interested in mathematics Signup and view all the answers

What is the term used to describe the tendency of an object to maintain its state of motion?

Inertia Signup and view all the answers

What is the significance of Archimedes' method in Galileo's book 'The Little Balance'?

It is used to find the density of substances Signup and view all the answers

What is the correct unit of momentum in the International System of Units?

kilogram-metre per second Signup and view all the answers

What is the relationship between the force applied to an object and the change in its momentum?

The force applied is directly proportional to the change in momentum Signup and view all the answers

What is the direction of the momentum of an object?

The direction of the velocity of the object Signup and view all the answers

What is the value of the constant of proportionality, k, in the equation F = kma?

1 Signup and view all the answers

What is the effect of a continuous push over some time on the momentum of an object?

It results in a gradual acceleration of the object Signup and view all the answers

What is the unit of acceleration in the International System of Units?

metre per second squared Signup and view all the answers

What is the relationship between the acceleration of an object and the force applied to it?

The acceleration of an object is directly proportional to the force applied to it Signup and view all the answers

What is the definition of one unit of force in the International System of Units?

The amount of force that produces an acceleration of 1 m s-2 in an object of 1 kg mass Signup and view all the answers

What is the primary reason why a fielder in a cricket match may get hurt while holding the catch?

The rate of change of momentum of the ball is large Signup and view all the answers

In a high jump athletic event, why are athletes made to fall on a cushioned bed or on a sand bed?

To increase the time of the athlete's fall to stop Signup and view all the answers

What is the primary reason why a karate player can break a slab of ice with a single blow?

The karate player is able to increase the rate of change of momentum Signup and view all the answers

An object of mass 5 kg is acted upon by a constant force for a duration of 3 s. If the velocity of the object increases from 3 m s-1 to 9 m s-1, what is the magnitude of the applied force?

15 N Signup and view all the answers

What is the velocity of the object after 5 s if the force is applied for a duration of 5 s, and the initial velocity is 3 m s-1?

17 m s-1 Signup and view all the answers

What is the relationship between the force applied and the rate of change of momentum of an object?

The force applied is directly proportional to the rate of change of momentum Signup and view all the answers

What is the effect of increasing the duration of the force applied on an object?

The rate of change of momentum decreases Signup and view all the answers

What is the formula to calculate the force applied on an object?

F = m*(v - u)/t Signup and view all the answers

Study Notes

Understanding Motion

Until Galileo Galilei and Isaac Newton, there was no comprehensive understanding of motion.
A force can be used to change the magnitude of velocity of an object or to change its direction of motion.
A force can also change the shape and size of objects.

Balanced and Unbalanced Forces

Balanced forces do not change the state of rest or motion of an object.
Unbalanced forces act on an object and bring it into motion.
When two opposite forces of different magnitudes pull an object, the object moves in the direction of the greater force.

Frictional Forces

Frictional forces arise between two surfaces in contact.
Frictional forces can balance or oppose the pushing force.

Inertia

An object maintains its motion under the continuous application of an unbalanced force.
When an object is suddenly stopped or changed in direction, it tends to continue in its original motion due to inertia.

Momentum

Momentum is defined as the product of an object's mass and velocity (p = mv).
The SI unit of momentum is kilogram-metre per second (kg m s-1).
Momentum has both direction and magnitude.

Force and Acceleration

The application of an unbalanced force brings a change in the velocity of an object and hence a change in momentum.
The rate of change of momentum is proportional to the force applied (F = km × (v - u) / t).
The unit of force is defined as the amount that produces an acceleration of 1 m s-2 in an object of 1 kg mass.

Real-World Applications

A continuous push over some time results in a gradual acceleration of an object.
A sudden application of force can result in a large change in momentum, which may cause harm or damage.
The concept of momentum and force is applied in various fields, such as sports and athletics, to ensure safety and optimize performance.

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Description

This quiz covers the concept of force and momentum in physics, including the effect of force on an object's motion and the relationship between force and momentum.