📚 Physics Study Set: Work, Power, Forces, and Newton’s Laws

What is work in science?

Applying a force to move an object in the same direction as the force.

What must be true for work to happen?

The object must move in the direction the force is applied.

What is the formula for work?

Work = force × distance

What units are used for work?

Joules (J)

What is power?

The rate at which work is done.

What is the formula for power?

Power = work ÷ time

What units are used for power?

Watts (W)

What do machines do?

Make work easier.

What is input force?

The force you apply to a machine.

What is output force?

The force the machine applies.

What is mechanical advantage?

How much a machine increases your force.

Why are machines not 100% efficient?

Because some energy has been lost through friction

If 100 J of work is done in 10 seconds, what is the power?

10 watts

What is inertia?

A property of matter that describes an object’s resistance to changes in its motion.

What does inertia cause an object at rest to do?

Stay at rest unless a force acts on it.

What does inertia cause an object in motion to do?

Stay in motion at the same speed and direction unless a force acts on it.

Which law summarizes the concept of inertia?

Newton’s First Law of Motion.

What happens to your body when a car suddenly stops?

Your body keeps moving forward due to inertia.

What must happen to change an object’s motion?

A force must act on it.

How does mass affect inertia?

The more mass an object has, the more inertia it has.

Which object has more inertia: a heavy object or a light object?

A heavy object.

Why is it harder to move a heavy object than a light one?

Because it has more inertia.

What is a Newton?

A unit of force equal to a unit of mass times a unit of acceleration.

What is the equation for one Newton?

1 Newton = 1 kg • m/s²

What unit is used to measure force?

Newtons (N)

What is the formula for Newton’s Second Law of Motion?

F = ma

What does “F” represent in the formula F = ma?

Force

What does “m” represent in the formula F = ma?

Mass

What does “a” represent in the formula F = ma?

Acceleration

What force is needed to accelerate a 400 g soccer ball at 5 m/s²?

2000 N

How are force and acceleration related according to Newton’s Second Law?

They are directly proportional (more force = more acceleration

How are mass and acceleration related according to Newton’s Second Law?

They are inversely proportional (more mass = less acceleration).

How can you increase acceleration?

Increase force or decrease mass.

What unit should mass be in when using F = ma?

Kilograms (kg)

What unit should acceleration be in when using F = ma?

Meters per second squared (m/s²)

What happens to acceleration if force increases and mass stays the same?

Acceleration increases.

What happens to acceleration if mass increases and force stays the same?

Acceleration decreases.

If you double the force on an object, what happens to acceleration?

It doubles

Why is it easier to push an empty cart than a full one?

The empty cart has less mass and less inertia.

How does inertia relate to Newton’s First Law?

Inertia is the reason objects resist changes in motion, as described in the law.

Why do heavier objects require more force to move?

Because they have more mass and more inertia.

How are work and force related?

Work depends on how much force is applied over a distance.

What happens to work if distance increases but force stays the same?

Work increases.

What happens to power if the same work is done in less time?

Power increases.