A small block of mass 20.0 grams is moving to the right on a horizontal friction
ID: 1424927 • Letter: A
Question
A small block of mass 20.0 grams is moving to the right on a horizontal frictionless surface with a speed of 0.460 m/s. The block has a head-on elastic collision with a 40.0 gram block that is initially at rest. Since the collision is head-on, all velocities lie along the same line, both before and after the collision.
(a) What is the speed of the 20.0 gram block after the collision?
m/s
(b) After the collision is the 20.0 gram block moving to the left or to the right?
(c) What is the speed of the 40.0 gram block after the collision?
m/s
(d) After the collision is the 40.0 gram block moving to the left or to the right?
Explanation / Answer
given masses are m1 = 20 g ,m2 = 40 g, u1 = 0.46 m/s, u2 = 0 m/s
velocity of the first object after collision is v1 = u1(m1-m2)/m1+m2
velocity of the second object after collision is v2 = 2m1u1/m1+m2
v1 = 0.46(20-40)/(20+40)= 0.46(-20*10^-3)/60*10^-3 = -0.153 m/s
moving in the negative x direction, towards left
v2 = 2*20*10^-3*0.46/60*10^-3 = 0.30 m/s
m2 will move in the positive x direction, mmove towards right