The coefficient of kinetic friction between a couch and the floor is 0.65. If the couch has a mass of 42 kg and you push it with a force of 600 N, what is the
net force on the couch as it slides?
A. 868 N
B. 188 N
C. 452 N
O D. 332 N

For general projectile motion, when the projectile is at the highest point of its trajectory, its acceleration is zero? a)the horizontal and vertical components of its velocity are zero. b) its velocity is perpendicular to the acceleration. c)the horizontal component of its velocity is zero. d)its velocity and acceleration are both zero.

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?

Considering only the earth's rotation, determine how much later the asteroid would have had to arrive to put the explosion above helsinki at longitude 25˚ e? this would have obliterated the city.