- #1

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A 900-kg car traveling east at 15.0 m/s collides with a 750-kg car traveling north at 20.0 m/s. The cars stick together. What is the speed of the wreckage just after the collision?

Relevant equations: m1v1 - m2v2 = (m1+ m2) vfinal

My attempt: This is an inelastic collision because the cars collide and stick together. So, momentum is conserved but kinetic energy is not.

2)A 1.80-kg block slides on a rough horizontal surface. The block hits a spring with a speed

of 2.00 m/s and compresses it a distance of 11.0 cm before coming to rest. If the coefficient

of kinetic friction between the block and the surface is μk = 0.560, what is the force

constant of the spring?

My attempt:

1/2mv2 - Mgd - 1/2kx = 0

mv2 -Mg

[(1.80kg)(2m/s)(2m/s) - (0.560)(10)]/0.1meters

k = 16 n x m