Two railway trucks of masses m and 3m move towards each other in opposite directions with speeds 2v and v respectively. these trucks collide and stick together. what is the speed of the trucks after the collision? a v/4 b v/2 c v d 5v/4

The correct answer is -v/4.

Explanation:

By applying equation of collision.

m1u1 + m2u2 = v(m1+m2).

The second object is moving in opposite direction so its momentum is negative. So, we have.

V= m1u1 + (-m2u2)/ m1 + m2

By imputing the data we have;

V = m×2v + (-3m×v)/ m+3m

V= 2mv - 3mv/ 4m

V = -mV/4m

V= -v/4//

NB: we have negative V because m2 is bigger than m1.

it will be pushed away from the source of the electric field. a negative charge in a cloud induces a positive charge in the ground below the cloud.

explanation: