1. A stone of mass
200g falls vertically for 2s and embeds itself
2cm in soft
mud.
(A) Assuming that the stone was released from rest, from what
height was it released?
(B) What is the average deceleration in the mud? (this is the
hard one)
(A) Using the kinematics equations,
s = ut + ½at²,
where u = 0, t = 2, and a = g = 10 (for O levels)
s = 0 + ½ (10)(2)² = 20m
(B) v = u + at
v = 0 + 10 * 2 = 20 m/s just before hitting the mud.
Using v² = u² - 2as, where a is the deceleration
s = 0.02m, v = 0, u = 20
0 = 20² - 2a(0.02)
a = 10000 m/s => please help confirm
2. If a hovercraft was travelling at 20m/s and its max uniform
acceleration is -1m/s, how long distance can it travel before
it comes to a halt?
Using v² = u² + 2as, where
a = -1
v = 0
u = 20
0 = 20² + 2(-1)s
s = 200m
Some more kinematics questions can be found here:
ExamWorld Kinematics