描述運動：速率、速度與加速度：練習題

If an object moves at a constant velocity, what can be said about its acceleration?

An athlete runs around a circular track of circumference \( 400 \text{ m} \) in \( 50 \text{ s} \). What is the athlete's average speed and average velocity for one complete lap?

Which unit is used to measure acceleration in the International System of Units (SI)?

A car accelerates from \( 10 \text{ m/s} \) to \( 30 \text{ m/s} \) over a distance of \( 80 \text{ m} \). Assuming constant acceleration, how much time did this take?

A runner starts from rest and reaches a velocity of \( 6 \text{ m/s} \) in \( 3 \text{ s} \). What is the runner's average acceleration?

A car decelerates uniformly from \( 20 \text{ m/s} \) to a complete stop in \( 5 \text{ seconds} \). What is the acceleration of the car?

In a displacement-time graph, what does the slope (gradient) of the line represent?

A train moves with a constant velocity of \( 25 \text{ m/s} \) for \( 10 \text{ seconds} \). What is the acceleration of the train during this period?

A sprinter runs a straight 100-meter race. He starts from rest and accelerates uniformly to reach his maximum speed of \(12 \text{ m/s}\) in the first \(4 \text{ seconds}\).

(a) Calculate the acceleration of the sprinter during the first 4 seconds.
(b) Calculate the distance traveled by the sprinter during this acceleration phase.

A delivery drone flies from its base to a drop-off point. It travels \(3000 \text{ meters}\) due North in \(5 \text{ minutes}\) and then immediately turns and travels \(4000 \text{ meters}\) due East in \(5 \text{ minutes}\).

(a) Calculate the drone's average speed for the entire trip in \(\text{m/s}\).
(b) Calculate the drone's average velocity for the entire trip (magnitude only) in \(\text{m/s}\).