Question

a block of mass 3kg has a velocity of um/s. when a force of 18N acts on the block, it reduces the velocity from u to u/2 after the block has covered a distance of 9m. find u?

Answer 1

this is your required answer

Answer 2

Answer:

Explanation:

Solution :-

Given :-

Mass, m = 3 kg

Force, F = 18 N

Initial Velocity, u = u m/s

Final Velocity, v = u/2 m/s

Distance, S = 9 m

To Calculate :-

Initial Velocity, u = ??

Formula to be used :-

v² - u² = 2as

or v² - u² = 2 × F/m × S (∵ a = Flm)

The value of a is negative because the final velocity is less than the initial velocity.

v² - u² = 2 × F/m × S

(u/2)² - u² = 2 × (- 18/3) × 9

u²/4 = - 108

u² - 4u² = - 432

u = 12 m/s

Hence, the initial velocity of block is 12 m/s.