A billiard ball traveling at 3.4 m/s has an elastic head-on collision with a billiard ball of equal mass that is initially at rest. The first ball is at rest after the collision. What is the speed of the second ball after the collision?

Explanation:

Given

Initial velocity of first billiard ball

Initial velocity of second billiard ball

After collision first ball comes to rest

suppose m is the mass of both the balls

Conserving momentum to get the speed of second ball after collision

Initial momentum

Final momentum

where and are the speed of first and second ball respectively

thus speed of second ball after collision is equal to speed of first ball before collision

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27