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Questions and Answers
How do you calculate the weight of an object if you know its mass?
How do you calculate the weight of an object if you know its mass?
Weight = mass * gravity
How do you calculate the normal force of an object on a surface?
How do you calculate the normal force of an object on a surface?
Normal force = how hard the table/floor/chair must push back.
How do you calculate the friction force on an object?
How do you calculate the friction force on an object?
Friction = mu * F_normal
Which forces are balanced if an object is accelerating to the right?
Which forces are balanced if an object is accelerating to the right?
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A man stands on a scale in an elevator. His mass is 80kg, but the scale reads 600 Newtons. What is his acceleration?
A man stands on a scale in an elevator. His mass is 80kg, but the scale reads 600 Newtons. What is his acceleration?
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How much speed does a boy gain while pulling a 25kg sled with a 300N force and a coefficient of friction of 0.2 in 3 seconds?
How much speed does a boy gain while pulling a 25kg sled with a 300N force and a coefficient of friction of 0.2 in 3 seconds?
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Use Newton's 2nd Law to explain why a baseball and golf ball will fall at the same speed.
Use Newton's 2nd Law to explain why a baseball and golf ball will fall at the same speed.
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Calculate the values of F_net and acceleration of a 3kg rocket while being pushed up by a 100N motor thrust.
Calculate the values of F_net and acceleration of a 3kg rocket while being pushed up by a 100N motor thrust.
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How does your mass compare on Earth vs. Mars?
How does your mass compare on Earth vs. Mars?
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Which planet would it be easier to lift a weight?
Which planet would it be easier to lift a weight?
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How could we get more traction when the back tires on a truck begin to spin out on the boat ramp?
How could we get more traction when the back tires on a truck begin to spin out on the boat ramp?
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The equation for net force can be represented as $F_{net} = $______ / m.
The equation for net force can be represented as $F_{net} = $______ / m.
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Study Notes
Forces Standard #1
- You must be able to identify the four main mechanical forces (gravity, normal force, friction, and tension) acting on an object based on a description of the force or the situation.
- You must be able to explain how changing any part of a force will affect its value.
- You must be able to calculate the exact value of each force and the Net Force acting on an object.
Forces Standard #2
- You must be able to use the calculated Net Force on an object to describe its resulting motion, for both objects at rest and those moving.
- You must be able to calculate the velocity change of an object based on its Net Force and duration of the forces.
- You must be able to predict how the motion will change if the Net Force changes.
Important Equations
- FnetF_{net}Fnet = ma (Net Force = mass x acceleration)
- FgF_gFg = mg (Force of gravity = mass x gravity)
- FfF_fFf = µFNF_NFN (Force of friction = coefficient of friction x Normal force)
- a = ΔvΔt\frac{\Delta v}{\Delta t}ΔtΔv (Acceleration = change in velocity / change in time)
Weight
- Weight is calculated by multiplying mass by gravity.
Normal Force
- The Normal force is how hard a surface pushes back on an object.
- If there are no other forces acting, the normal force is equal to the object's weight.
- You must take into account any pushing or pulling forces that might be acting on the object.
Friction
- The force of friction is calculated by multiplying the coefficient of friction by the normal force.
Balanced Forces
- If an object is at rest or moving at a constant speed, the forces acting on it are balanced.
- If the forces are not balanced, the object will accelerate.
Acceleration
- You can calculate the acceleration of an object from the Net Force and mass using the equation FnetF_{net}Fnet = ma.
- If the object has constant velocity, the acceleration is zero.
Gravity
- Gravity is the same on Earth and Mars, but the acceleration due to gravity ggg is different.
- Your mass is the same on both planets, but your weight is different.
- It is easier to lift a weight on Mars than on Earth because of the difference in gravity.
- It is equally easy to push a sled across a frictionless surface on both planets.
Traction
- Traction is the force that prevents your tires from slipping on a surface.
- Traction can be increased by adding sand, salt, or other materials to the surface to increase the grip.
- Traction can also be increased by adding weight to the back of the vehicle to increase the normal force.
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Description
Test your understanding of the four main mechanical forces: gravity, normal force, friction, and tension. This quiz covers identifying these forces, calculating their values, and understanding their effects on motion. Additionally, you'll explore important equations connected to net force and acceleration.
