Question

Suppose a ball is thrown straight up. What is its acceleration just before it reaches its highest point? a. Slightly greater than g b. Zero c. Exactly g d. Slightly less than g Which of Newton's laws best explains why motorists should buckle-up? Newton's First Law a. b. Newton's Second Law c. Newton's Third Law d. None of the above Which one of the following Newton's laws best illustrates the scenario of the thrust of an aircraft generated by ejecting the exhaust gas from the jet engine? a. Newton's First Law b. Newton's Second Law c. Newton's Third Law d. None of the aboveWhich of the statements is correct in describing mass and weight? a. They are exactly equal b. They are both measured in kilograms c. They both measure the same thing d. They are two different quantities A bomb is fired upwards from a cannon on the ground to the sky. Compare its kinetic energy K, to its potential energy U a. K decreases and U decreases b. K increases and U increases C. K decreases and U increases d. K increases and U decreases

Answer 1

1. When the ball reaches its highest point, its velocity becomes zero. At this point, its acceleration is equal to the acceleration due to gravity (g). Therefore, the correct answer is c. Exactly g.

2. The best explanation for why motorists should buckle-up is Newton's First Law, which states that an object at rest tends to stay at rest, and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an external force. When a car suddenly stops or crashes, the passengers inside the car will continue moving at the same speed and in the same direction unless they are restrained by seatbelts. Therefore, the correct answer is a. Newton's First Law.

3. The scenario of the thrust of an aircraft generated by ejecting the exhaust gas from the jet engine is best explained by Newton's Third Law, which states that for every action, there is an equal and opposite reaction. The exhaust gas is expelled from the jet engine with a force, and as a result, the aircraft experiences an equal and opposite force that propels it forward. Therefore, the correct answer is c. Newton's Third Law.

4. Mass and weight are two different quantities. Mass is a measure of the amount of matter in an object and is measured in kilograms. Weight, on the other hand, is the force exerted on an object due to gravity and is measured in Newtons. Therefore, the correct answer is d. They are two different quantities.

5. When the bomb is fired upwards, its kinetic energy (K) decreases as it loses velocity due to the opposing force of gravity. At the same time, its potential energy (U) increases as it gains height in the gravitational field. Therefore, the correct answer is c. K decreases and U increases.