Forces and Motion Investigation Quiz

Which of the following best describes Newton's Second Law of Motion?

• An object at rest stays at rest unless acted on by a force.

• The acceleration of an object depends on the net force acting on it and its mass.

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

• Objects fall at the same rate regardless of mass.

Answer explanation

Newton's Second Law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass, making this choice the best description of the law.

If the net force on an object is zero, the motion of the object will (a)   .

• It will speed up.
• It will slow down.
• It will continue moving at the same
• It will change direction.

Answer explanation

If the net force on an object is zero, it means there is no change in motion. Therefore, the object will either continue moving at the same velocity or remain at rest.

Which equation correctly represents Newton's Second Law?

Answer explanation

Newton's Second Law states that the force (F) acting on an object is equal to the mass (m) of the object multiplied by its acceleration (a), represented by the equation F = m × a. This is the correct choice.

If you double the mass of an object but apply the same force, what happens to its acceleration?

• It doubles.

• It stays the same.

• It is cut in half.

• It becomes zero.

Answer explanation

According to Newton's second law (F = ma), if you double the mass (m) while keeping the force (F) constant, the acceleration (a) is halved. Thus, the correct answer is that the acceleration is cut in half.

Which scenario describes balanced forces acting on an object?

• A book resting on a table.

• A car speeding up.

• A ball falling to the ground.

• A person pushing a box and it starts moving.

Answer explanation

A book resting on a table experiences balanced forces: the downward force of gravity is equal to the upward normal force from the table, resulting in no net force and no movement.

Match each scenario with its correct acceleration. (Use Newton's Second Law: F = ma)

• A 10 kg object is pushed with a net force of 20 N.

• A 0.1 kg object is pushed with a net force of 20 N.

• A 2 kg object is pushed with a net force of 20 N.

• A 40 kg object is pushed with a net force of 20 N.

Answer explanation

Using Newton's second law, F = ma, we can find acceleration (a) by rearranging the formula: a = F/m. Here, F = 20 N and m = 10 kg. Thus, a = 20 N / 10 kg = 2 m/s². The correct answer is 2 m/s².

Which of the following best describes unbalanced forces?

• Forces that are equal in size and opposite in direction.

• Forces that cause a change in an object's motion.

• Forces that cancel each other out.

• Forces that keep an object at rest.

Answer explanation

Unbalanced forces are those that do not cancel each other out and result in a change in an object's motion, unlike balanced forces which are equal in size and opposite in direction.

Answer explanation

To find the net force, use Newton's second law: F = m * a. Here, m = 5 kg and a = 4 m/s². Thus, F = 5 kg * 4 m/s² = 20 N. The correct answer is 20 N.

A student wants to investigate how mass affects acceleration when the same force is applied. Which setup would best test this?

• Use objects of different masses and apply the same force to each.

• Use the same object and apply different forces.

• Use objects of the same mass and apply the same force.

• Use objects of different masses and apply different forces.

Answer explanation

To investigate how mass affects acceleration with the same force, using objects of different masses while applying the same force allows for direct comparison of acceleration changes, confirming Newton's second law.

A cart is pushed with a constant force. If the mass of the cart is increased, what must happen to the force to keep the same acceleration?

• The force must decrease.

• The force must stay the same.

• The force must increase.

• The force must be zero.

Answer explanation

According to Newton's second law (F = ma), if the mass (m) of the cart increases and we want to maintain the same acceleration (a), the force (F) must increase to compensate for the greater mass.