Question

a 5kg ball is thrown upwardwith a speed of 10m/s

a. calculate the max. height attained by it.

b. find the potential energy when it reaches the highest point.

Answer 1

(a)

we know that

v² - u² = 2as

or

s = (v² - u²) / 2a

now for height 's' to be maximum v = 0 (final velocity is zero)

and given

u = 10 m/s

and also a = -g = -9.81 m/s²

so,

s = (0² - 10²) / 2x-9.81

or

s = -100 / -19.62

thus, max height attained will be

s = 5.096 m

.

(b)

now, the potential energy is given as

PE = mgs

here m = 5kg

so,

PE = 5 x 9.81 x 5.096

thus,

PE = 249.9 ~ 250 J