In an elastic collision, a rigid sphere moving with velocity v1 collided head-on with another sphere of equal mass moving toward it, as shown in the picture. The second sphere had a velocity 2v1. What was the change in velocity of the first sphere after the collision?
A) v1, moving from left to right
B) v1, moving from right to left
C) 2v1, moving from left to right
D) 2v1, moving from right to left

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.

Aperson walks first at a constant speed of 4.89 m/s along a straight line from point a to point b and then back along the line from b to a at a constant speed of 2.95 m/s. what is the average speed over the entire trip?

Directions: count the number of atoms. ar co2 na3po4 so3 nac2h3o2