Sec 3 Combined Science (Physics) Motion topical questions

State the equation used to calculate average speed, and name the units of each quantity in SI.

A bus travels 1500 m in 60 s. Calculate its average speed.

State what is meant by the acceleration of free fall, and give its value used in this course.

On a speed–time graph, state what (a) the gradient and (b) the area under the line represent.

A car accelerates uniformly from rest to 24 m/s in 8.0 s. Calculate the acceleration, and state the speed of the car 3.0 s after starting (still accelerating uniformly).

Describe, in terms of gradients, how to distinguish on a distance–time graph: (a) rest, (b) constant speed, (c) speeding up, (d) slowing down.

A speed–time graph shows a car: accelerating uniformly from 0 to 15 m/s over 10 s, then constant 15 m/s for 20 s, then decelerating uniformly to rest over 5.0 s. Calculate (a) the acceleration in the first stage, (b) the deceleration in the last stage, and (c) the total distance travelled.

A coach travels 30 km in 0.50 h, stops for 0.25 h, then travels 45 km in 0.75 h. (a) Calculate the average speed for the whole journey in km/h. (b) Explain why the stop lowers this average. (c) The moving average while driving (excluding the stop) is 60 km/h — show this and explain the difference.

A stone is dropped down a well and hits the water 1.8 s later. Taking g = 10 m/s² and ignoring air effects: (a) calculate its speed as it hits the water; (b) estimate the depth of the well using the area under a speed–time graph; (c) state one reason the real depth may differ slightly.

Two cyclists leave the same point together. Cyclist A rides at a steady 6.0 m/s. Cyclist B starts from rest and accelerates uniformly, overtaking A after 60 s, both having covered the same distance. (a) Calculate the distance. (b) Calculate B's acceleration. (c) State B's speed at 60 s and comment on the comparison with A.

A lift rises: it accelerates uniformly from rest to 4.0 m/s in 2.0 s, travels at 4.0 m/s for 12 s, then decelerates uniformly to rest in 4.0 s. (a) Sketch the speed–time graph in words and (b) find the total distance. (c) Find the average speed for the whole journey and (d) explain why it is less than 4.0 m/s.

A student claims: "On any motion graph, a straight line always means constant speed." (a) State when this is true and when it is false, referring to both graph types. (b) A speed–time line rises from 5.0 m/s to 25 m/s over 10 s. Find the acceleration and the distance travelled. (c) Explain why the distance is not simply 25 × 10.