Question

.Ball thrown vertically upwards return to its starting point in 4s. If a is 10m/s?, its initial speed was

Answer 1

Answer:

Explanation:

we can use newton's three formulae

• v = u + at
• s = ut + 1/2 at^2

• v^2 = u^2 + 2as

and if we have negative acceleration than instead of + we will put -

so the time taken for the whole journey of the ball is 2u/g

here u is the velocity at time t=0sec

and g is the acceleration due to the gravity= 10m/s

∴ 4 = 2u/10

∴u = 20m/s

hope it is helpful..............................