Question

A body is dropped from a height of 320m. the acceleration is 10m/s²

(a) How long does it take to reach the ground?
(b) What is the velocity with which it will strike the ground?

Please answer according to class 9th class

Answer 1

Answer:

a) 8 seconds

b) 80 m/s

Explanation:

given,

the height from which a body is dropped = 320

given acceleration at which it fall =

10m/s²

now,

given,

Height (s) = 320 m

gravitational acceleration(g) = 10m/s²

initial velocity(u) = 0m/s [it was at rest]

(a) How long does it take to reach the ground?

➡By the gravitational motion formulae

S = ut + 1/2gt²

putting the values

320 = 0(t) + 1/2 × 10 × t²

5t² = 320

t² = 320/5

t² = 64

t = 8 seconds

(b) What is the velocity with which it will strike the ground?

➡ by the gravitional motion formulae

v² = u² + 2gS

where,

v = final velocity [velocity with which it will strike the ground]

putting the values

v² = (0)² + ( 2 × 10 × 320)

v² = 6400

v = 80 m/s

so,

velocity with which it will strike the ground = 80m/s