Answer:
68cm
Explanation:
You can solve this problem by using the momentum conservation and energy conservation. By using the conservation of the momentum you get

m: mass of the bullet
M: mass of the pendulum
v1: velocity of the bullet = 410m/s
v2: velocity of the pendulum =0m/s
v: velocity of both bullet ad pendulum joint
By replacing you can find v:

this value of v is used as the velocity of the total kinetic energy of the block of pendulum and bullet. This energy equals the potential energy for the maximum height reached by the block:

g: 9.8/s^2
h: height
By doing h the subject of the equation and replacing you obtain:

hence, the heigth is 68cm
I think the answer would be C
Atmospheric electricity and storms,electric current in a vacuum,spark discharge,electrostatic control filters and industrial electrostatic separation <- those are just a few
Answer:
-20N
Explanation:
The racquet ball will bounce back with the same force.
This is in compliance with newton's third law of motion:
"action and reaction are equal but opposite"
If the ball hits the wall with an action force of 20N, the reaction force will be -20N.
The negative indicates an oppositely directed force.