Anita is bouncing a tennis ball on the sidewalk. She drops the ball and then watches it bounce back up. At which point does Anita's tennis ball have zero kinetic energy? A

as it hits the sidewalk's surface

B

just after it hits the sidewalk's surface

С

as it begins to fall to the sidewalk

D

just as it reaches the top of the bounce

Just as it reaches the top of the bounce.

Explanation:

When an object reaches to the maximum height, its kinetic energy is equal to 0. It can be calculated as follows :

Where

m is mass and v is velocity

In this problem, Anita is bouncing a tennis ball on the sidewalk. She drops the ball and then watches it bounce back up.

It means, when it reaches the top of the bounce, Anita's tennis ball have zero kinetic energy. Hence, the correct option is (d).

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

your answer is, orbit around the nucleus