(a) Distinguish between perfectly elastic collision and perfectly inelastic collision.
(b) Sketch a distance — time graph for a particle moving in a straight line with:
(i) uniform speed;
(ii) variable speed.
(c) A body starts from rest and travels distances of 120, 300 and 180m in successive equal time intervals of 12 s. During each interval the body is uniformly accelerated. (i) Calculate the velocity of the body at the end of each successive time interval.
(ii) Sketch a velocity-time graph for the motion.
Explanation
|
Perfectly Elastic |
Perfectly Inelastic |
|
K.E. is conserved Colliding objects do not stick together after collision In case of head-on collision directions of the bodies are reversed |
K.E. decreases Colliding objects stick and move together after collision Direction of both bodies may or may not be reserved |
(b)
(c)(i) Stage 1; S = ut + (frac{1}{2}at^2)
= 120 = 0 x 12 + (frac{1}{2}) x a x 12(^2)
a = (frac{5}{3})
(V_1 = u + at)
= 20 + (frac{5}{6} times 12 = 30m/s)
Stage 3; S = ut + (frac{1}{2}) at(^2)
-180 = 30 x 12v + (frac{1}{2}) x a x 12(^2)
a = (frac{-5}{2})
V(_3) = u + at = 30 + (frac{-5}{2}) x 12 = 0m/s
(ii) v/m(^{s – 1})