SC8 Q1

Which of the following is the cause of acceleration or a change to an object's motion?

• Balanced Force

• Unbalanced Force

Answer explanation

An unbalanced force is necessary to cause acceleration or change an object's motion, as it overcomes inertia. In contrast, balanced forces do not result in motion changes.

Which of the following is equivalent to the unit of force, Newton?

• Mass (Kg) x Acceleration (m/s2)

• Distance (m) x Acceleration (m/s2)

Answer explanation

The Newton (N) is defined as the force required to accelerate a 1 kg mass by 1 m/s². Therefore, it is equivalent to Mass (Kg) x Acceleration (m/s²), making this the correct choice.

Ignoring Friction, what happens to the speed of an object with a constant mass if the force applied on it increases?

• The object will not move

• It moves faster

Answer explanation

According to Newton's second law, force equals mass times acceleration (F=ma). If the force increases while the mass remains constant, the acceleration increases, leading to a higher speed. Therefore, the object moves faster.

An athlete is participating for an upcoming triathlon. How much force does he need to accelerate his bicycle to 2 m/s2 as a warmup if the combined weight of the athlete and his bicycle is 60 kilograms?

• 120 N

• 30 N

Answer explanation

To find the force needed, use Newton's second law: F = m * a. Here, m = 60 kg and a = 2 m/s². Thus, F = 60 kg * 2 m/s² = 120 N. Therefore, the correct answer is 120 N.

Which of the following states the second law of motion when a constant force is applied on an object?

• Acceleration decreases as its mass increases.

• Acceleration increases as its mass remains the same.

Answer explanation

According to Newton's second law, acceleration (a) is inversely proportional to mass (m) when a constant force (F) is applied (F = ma). Thus, if mass decreases, acceleration increases, making the correct choice "Acceleration decreases as its mass decreases".

What is the net force in the figure?

• 25 N, to the right

• 195 N, to the left

Answer explanation

The net force is calculated by summing the forces acting in each direction. If the forces to the right total 25 N and there are no opposing forces to the left, the net force is 25 N, to the right.

Which of the following would a one Newton force cause?

• Gives a 1 kg mass an acceleration of 1 m/s2

• Gives a 0.1 kg mass an acceleration of 10 m/s2

Answer explanation

According to Newton's second law (F=ma), a 1 Newton force applied to a 1 kg mass results in an acceleration of 1 m/s². Thus, the correct choice is 'Gives a 1 kg mass an acceleration of 1 m/s²'.

Which law states that when two objects interact, they exert equal amount of force to one another but opposite in direction?

• Law of Action and Reaction

• Law of Acceleration

Answer explanation

The Law of Action and Reaction, also known as Newton's Third Law, states that for every action, there is an equal and opposite reaction. This means that when two objects interact, they exert equal forces on each other in opposite directions.

When a ball is dropped and hits the ground, which body experiences the larger magnitude of force?

• Only the ground experiences the larger magnitude of force

• Both ground and the ball experience the same magnitude of force

Answer explanation

According to Newton's third law, when the ball hits the ground, both the ball and the ground exert equal and opposite forces on each other. Therefore, both experience the same magnitude of force.

Which of the following statements below is an example of Newton's Third Law?

• When you put a book on the table and the table exerts force on the book.

• A ball accelerates when force is applied on it

Answer explanation

The correct choice illustrates Newton's Third Law, which states that for every action, there is an equal and opposite reaction. The table exerts an upward force on the book, balancing the downward force of gravity.