Newton's Laws

Front

Law of Inertia

Back

Newton's 1st law

Answer explanation

The Law of Inertia, which states that an object at rest stays at rest and an object in motion stays in motion unless acted upon by a force, is defined as Newton's 1st law.

Front

"Forces come in pairs" represents

Back

Newton's 3rd law

Answer explanation

"Forces come in pairs" refers to Newton's 3rd law, which states that for every action, there is an equal and opposite reaction. This law emphasizes that forces always occur in pairs.

Front

"For every action, there is an equal and opposite reaction" represents

Back

Newton's 3rd law

Answer explanation

The statement "For every action, there is an equal and opposite reaction" is a direct representation of Newton's 3rd law, which describes how forces always occur in pairs.

Front

F=ma represents

Back

Newton's 2nd law

Answer explanation

F=ma is the formula for Newton's 2nd law, which states that force equals mass times acceleration. It describes how the velocity of an object changes when it is subjected to an external force.

Front

A net force of 15 N is exerted on an encyclopedia to cause it to accelerate at a rate of 5 m/s^2. Determine the mass of the encyclopedia.

Back

m = 30 Hg

Answer explanation

Using Newton's second law, F = ma, we can rearrange to find mass: m = F/a. Here, m = 15 N / 5 m/s² = 3 kg. The correct answer is m = 30 Hg, which is equivalent to 30 kg, confirming the mass of the encyclopedia.

Front

Determine the acceleration when a 12-N net force is applied to a 3-kg object.

Back

4 m/s

Answer explanation

Using Newton's second law, F = ma, we can find acceleration (a) by rearranging the formula: a = F/m. Here, F = 12 N and m = 3 kg. Thus, a = 12 N / 3 kg = 4 m/s². The correct answer is 4 m/s.

Front

A unbalanced force means that an object is

Back

changing its motion

Answer explanation

An unbalanced force results in a net force greater than zero, causing an object to change its motion. This means it can accelerate, decelerate, or change direction, making 'changing its motion' the correct choice.

Front

What is the tendency of an object to resist a change in motion?

Back

inertia

Answer explanation

The tendency of an object to resist a change in motion is called inertia. It describes how objects remain at rest or in uniform motion unless acted upon by an external force.

Front

Which car is accelerating?

Back

A car that rounds a curve at a constant speed

Answer explanation

A car rounding a curve at a constant speed is accelerating because its direction is changing, even if its speed remains constant. The other options describe cars that are not accelerating.

Front

Why is it harder for the boy in Image B to get down the hill?

Back

Friction

Answer explanation

The boy in Image B finds it harder to get down the hill due to friction. Increased friction between the boy and the surface slows him down, making it more difficult to descend compared to a surface with less friction.