A 2-kg block slides along a rough horizontal surface and slows to 10 m/s after traveling 20 m. If the kinetic coefficient of friction between the block and surface is 0.2, the initial speed (m/s) of the block was most nearly:

initial speed is 13.36 m/s

Explanation:

given data

mass = 2 kg

velocity = 10 m/s

distance = 20 m

friction = 0.2

to find out

initial speed

solution

we find first friction force that is

friction force = friction * mass*g ... 1

put here value

friction force = 0.2 * 2 * 9.81

friction force = 3.924 N

here a will be - ve due to friction

- friction force = mass * acceleration

acceleration = - friction force / mass

acceleration = - 3.924 / 2

acceleration = - 1.962 m/s²

and we know velocity formula that is

V² = V (i) ² + 2as

put here value

10² = V (i) ² + 2 (-1.962) (20)

V (i) = 13.36

so initial speed is 13.36 m/s