Aball is thrown vertically upward with a speed of 25.0 m/s. (a) how high does it rise? (b) how long does it take to reach its highest point? (c) how long does the ball take to hit the ground after it reaches its highest point? (d) what is its velocity when it returns to the level from which it started?

(a) 31.25 m

(b) 5 second

(c) 25 m/s

Explanation:

u = 25 m/s , g = 10 m/s^2

(a) Let the ball rises upto height h

use third equation of motion

v^2 = u^2 - 2 g h

The final velocity v is zero at maximum height

0 = 25^2 - 2 x 10 x h

625/20 = h

h = 31.25 m

(b) Let it reaches to maximum height in time t

use first equation of motion

v = u - g t

0 = 25 - 10 x t

t = 2.5 s

It takes T time to reach the ground.

T = 2 t = 2 x 2.5 = 5 s

(c) Let it reaches the ground with velocity v

Use third equation of motion

v^2 = u^2 + 2 g h

v^2 = 0 + 2 x 10 x 31.25

v = 25 m/s

the current is 0.6

voltage ÷ resistance = current

so 12 ÷ 20 = 0.6