Questions
1. A
toy truck with a mass of 3 kg was moving at 3 ms-1 and hit with
another toy truck of 1 kg and was moving with a velocity of 1 ms-1,
in the opposite direction. After collision, both trucks moved together in the
same direction, calculate the common velocity of the two objects after
collision.
m1u1 + m2u2 = (m1+ m2)v
(3)(3) + (1)(-1) = (3+1)v
9 – 1 = 4v
v = 2 ms-1
2.
A hunter shot a 100g
bullet from a 1.5kg gun. If the bullet travelled 200 ms-1 after being
triggered, what is the backward jerk of the gun. (Think final backward velocity
of the gun).
Total initial momentum = Total final momentum = 0
m1u1 + m2u2 = 0
1.5(v) + 0.1(200) = 0 ß make sure to convert 100g to kg
1.5v +20 = 0
v = - 13.3 ms-1 ß Value is negative because gun moved in opposite direction
3.
A trolley of mass
2 kg was in a stationary condition, before a 5 g sticky plasticine was thrown
into it with a velocity of 500 ms-1. After hitting the trolley, the plasticine
sticks into it. Calculate the final velocity of both the trolley and
plasticine?
Use the classic formula of momentum conservation
m1u1 + m2u2 = m1v1 + m2v2
0.005 (500) + 2 (0) = (0.005+ 2)v
2.5 = 2.005v
v = 1.245 ms-1
