A2-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

see earlier answer

beta is electron from nucleus

something from nucleus has changed, but charge must be same for cons of charge