A person ties a rock to a string and whirls it around in a ...

[joesmith1212]

A person ties a rock to a string and whirls it around in a vertical circle such that sometimes the rock is going straight upward and sometimes the rock is going straight down.
 
  She whirls the rock at the minimum speed (constant in time) such that the string is always taut (no sag). If she were to use a longer string, she would have to whirl the rock at a
  A) higher velocity.
  B) lower velocity.
  C) the same velocity.

Question 2

A 2.00-kg object traveling east at 20.0 m/s collides with a 3.00-kg object traveling west at 10.0 m/s. After the collision, the 2.00-kg object has a velocity 5.00 m/s to the west. How much kinetic energy was lost during the collision?
 
  A) 91.7 J B) 0.000 J C) 458 J D) 175 J E) 516 J

[Anton]

Answer to Question 1

A

Answer to Question 2

C

[joesmith1212]

Excellent

[amcvicar]

Gracias!