Forces

Inertia

The tendency of an object to resist changes in its state of motion.

Does every object have inertia?

Yes, all objects have inertia.

What is the standard metric unit of mass?

The kilogram (kg).

Is mass dependent on gravity?

No, mass is independent of gravity.

How is mass related to weight?

Weight is the force exerted by gravity on an object's mass.

What does weight measure?

The force of gravity acting on an object.

Would an object weigh less on the Moon than on Earth?

Yes, an object would weigh less on the Moon due to weaker gravitational pull.

What happens to an object when balanced forces act on it?

The object remains at rest or continues to move at constant velocity.

What is required to change the motion of an object?

An unbalanced force is required to change the motion.

What does Newton’s First Law state?

An object in motion stays in motion, and an object at rest stays at rest unless acted upon by an unbalanced force.

Does a moving object require a force to keep moving at constant velocity?

No, a moving object does not require an external force to keep moving at constant velocity.

What is a force?

A push or pull acting on an object.

Is force a vector or scalar quantity?

Force is a vector quantity.

Can an object experience multiple forces and not accelerate?

Yes, if the net force is zero, an object can experience multiple forces and not accelerate.

What is the metric unit of force?

The Newton (N).

According to Newton's Second Law, what does acceleration depend on?

Acceleration depends on the net force acting on an object and its mass.

If net force increases and mass stays the same, what happens to acceleration?

Acceleration increases.

If mass increases and net force stays the same, what happens to acceleration?

Acceleration decreases.

What is the formula for Newton's Second Law?

F = ma (Force = mass x acceleration).

If an object is accelerating to the right, in which direction is the net force?

The net force is directed to the right.

If an object is moving right but slowing down, which way is the net force?

The net force is directed to the left.

What does Newton's Third Law state?

For every action, there is an equal and opposite reaction.

Why don't action and reaction forces cancel each other out?

They act on different objects.

What is the reaction force to gravity acting on you when you sit on a chair?

The normal force exerted by the chair.

When a golf club hits a ball, how does the force on the ball compare to the force on the club?

The forces on the ball and the club are equal in magnitude and opposite in direction.

In the same scenario, which accelerates more: the ball or the club?

The ball accelerates more due to having less mass than the club.

What is Big Bubba’s mass on the Moon if it is 100 kg on Earth?

100 kg (mass remains the same regardless of location).

If Little Billie weighs 360 N on Earth, what is their mass on the Moon?

Mass remains the same; use the weight to find Earth mass, then apply the Moon's gravity if needed.

True or false: An object moving rightward always has a rightward force acting on it.

False, an object can move rightward with balanced forces.

How much net force is needed to keep a 5-kg object moving rightward at constant velocity?

Zero net force is needed; balanced forces keep it moving at constant velocity.

According to Newton’s Laws, what must be true of the forces acting on an object moving at constant speed in a straight line?

The net force acting on the object must be zero.

What happens to the net force when an object moves at constant velocity?

The net force is zero.

In a velocity-time graph, during which intervals are the forces balanced?

Where the velocity is constant (slope is zero).

In a dot diagram, during which intervals is there a net force acting on the object?

Where the spacing of dots increases or decreases.

What is the net force on a 2-kg box in free fall?

The weight of the box, which equals its mass times the acceleration due to gravity.

What forces act on a box falling at terminal velocity?

The gravitational force and the drag force are equal.

If a box is pushed with an 8-N force and encounters 5 N of friction, what is the net force?

The net force is 3 N in the direction of the applied force.

If a freight elevator descends at constant velocity, what can you say about the net force?

The net force is zero.

How do you calculate the acceleration of a skydiver given mass and air resistance?

Apply Newton's Second Law, accounting for net force which is weight minus air resistance.

If a 1.05-kg object is pushed with 5.20 N, what is its acceleration?

Acceleration = 5.20 N / 1.05 kg = 4.95 m/s².

If friction is present, how does it affect the acceleration of an object?

Friction opposes motion, reducing acceleration.

How do you find the applied force needed to overcome friction and accelerate an object?

Add the force of friction to the desired net force needed for acceleration.

How do you calculate the average resistive force on a car that stops over a given time?

Use the change in momentum over the time taken to stop.

How do you determine the resistive force acting on a glider slowing down on an air track?

Measure the deceleration and use it with the mass to find the resistive force.