Quiz

Let's go through each question:

Question 1: When a distance-time graph shows a straight horizontal line for distance, that means the car is not moving.
Answer: true. A horizontal line on a distance-time graph indicates that there is no change in distance over time, meaning the car is stationary.

Question 2: A cyclist slows down at the end of the race. His velocity changes from 2 m/s to 6 m/s during a period of 4 seconds without any change in direction. What was his average acceleration during these 4 seconds?
To calculate average acceleration:
Average acceleration = (final velocity - initial velocity) / time
= (6 m/s - 2 m/s) / 4 s
= 4 m/s / 4 s
= 1 m/s².
Answer: 1 m/s².

Question 3: If the direction changes, it does not affect the acceleration of an object.
Answer: false. If the direction changes, the acceleration can be affected, as acceleration is a vector quantity and depends on both the magnitude and the direction.

Question 4: If the velocity changes, it does not affect the acceleration of an object.
Answer: false. Acceleration is defined as the rate of change of velocity; therefore, a change in velocity directly affects the acceleration.

Question 5: When a distance-time graph shows a straight horizontal line for distance, that means the car is moving at a constant speed.
Answer: false. A horizontal line indicates the car is not moving at all, rather than moving at a constant speed.

Final answers:

1. true
2. 1 m/s²
3. false
4. false
5. false