Theory question 107
Dynamics(a) The speed of a moving bus reduced from 45 ms−1 to 5 ms−1 with a uniform retardation of 10 ms−2. Calculate the distance covered. (b) A bucket full of water with mass 16 kg is pulled out of a well with a light inextensible rope. Find its acceleration when the tension in the rope is 240 N. [Take g = 10 ms−2]
Show the model answer
Model answer
(a) v² = u² + 2as: 25 = 2025 − 20s, so s = 100 m.
(b) T − mg = ma: 240 − 160 = 16a, a = 5 ms⁻² (upwards).
Explanation
A retardation is a negative acceleration.