Newton's Second Law

Newton's Second Law

Middle School

​

Learning Objectives

Key Vocabulary

​

Acceleration

The rate of change in an object's velocity, measured in meters per second squared (m/s²).

​

Force

Any push or pull that can cause an object to accelerate, measured in Newtons (N).

​

Mass

The measure of an object's inertia or the amount of matter it contains, measured in kilograms (kg).

​

Net Force

The overall force on an object when all individual forces acting on it are added together.

​

Weight

​

Friction

The force that opposes motion when two surfaces are in contact with each other.

​

​

What is Newton's Second Law?

Multiple Choice

According to Newton's Second Law, what is the relationship between an object's mass and its acceleration when a constant net force is applied?

• They are directly proportional; as mass increases, acceleration increases.

• They are inversely proportional; as mass increases, acceleration decreases.

• They are equal; mass is always the same as acceleration.

• There is no relationship between mass and acceleration.

​

​

The Formula for Force

Multiple Choice

How much net force is required to accelerate a 20 kg bike at 10 m/s²?

• 2 N

• 30 N

• 200 N

• 0.5 N

Identifying Common Forces

​

Force of Gravity

​

Normal Force

​

Friction

Multiple Choice

What is the name for the force of gravity acting on an object, calculated by multiplying its mass by the acceleration due to gravity (g)?

• Normal Force

• Net Force

• Friction

• Weight

​

Common Misconceptions

Misconception	Correction
Mass and weight are the same thing.	Mass is the amount of matter. Weight is the force of gravity on that mass.
A large force is always required to accelerate a massive object.	Acceleration depends on the net force. A small net force causes slow acceleration.
The normal force is always equal to an object's weight.	Normal force equals weight only on a flat, horizontal surface.

Multiple Choice

A car has a mass of 2500 kg and experiences a net force of 5000 N. What is the car's acceleration?

• 0.5 m/s²

• 2 m/s²

• 2500 m/s²

• 12,500,000 m/s²

Multiple Choice

If you apply the same net force to a bowling ball and a golf ball, why does the golf ball have a much larger acceleration?

• Because the golf ball is heavier, so the force has more effect.

• Because the bowling ball has more inertia, resisting the change in motion more.

• Because the force of gravity on the golf ball is stronger.

• Because the golf ball has less friction acting on it.

Multiple Choice

A box is sliding down a ramp at a constant speed. According to Newton's Second Law, what can you conclude about the forces acting on the box?

• The force of gravity is the only force acting on it.

• The force of friction is stronger than the force of gravity pulling it down the ramp.

• The net force on the box is zero.

• The normal force is causing the box to accelerate.

Multiple Choice

To solve for the force of friction on an object, you need to know the coefficient of friction and what other value?

• The object's mass

• The object's acceleration

• The normal force

• The force of gravity

​

Summary

Poll

On a scale of 1-4, how confident are you about applying Newton's Second Law to solve problems?

• 1

• 2

• 3

• 4