A cart of mass m is moving with negligible friction along a track with known speed v to the right. It collides 1 with and sticks to a cart of mass 4m moving with known speed v to the right. Which of the two principles, 2 conservation of momentum and conservation of mechanical energy, must be applied to determine the final speed of the carts, and why

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.

electrical potential energy =0.072 j

explanation:

electrical potential energy is given by

u= q δv

q= charge=6 c

δv= potential difference and is given by

δv= e d

e= electric field

d= distance=5 mm=0.005 m

δv=2.4 (0.005)=0.012 v

now electric potential energy= u= q δv

u=6 (0.012)

u=0.072 j