An object with a mass of 15 kg is moving at 9 m/s over a surface with a kinetic friction coefficient of 4 . How much power will it take to accelerate the object at #3 m/s^2?

2 Answers
Jan 13, 2018

Frictional force acting on the object is fk= u* N or, umg i.e 600 N,
So, let's assume we will be requiring a force of F to accelerate the object at 3 (m/sec^2)
So,using equation of force we can write,
(F - fk) = ma
Or, F = (15*3)+600 N i.e 645 N
Now,if this force cause displacement s of the object wi th in time t,power will be (work done/time) i.e 645(s/t)

Jan 13, 2018

The power is =5.697kW

Explanation:

The mass of the object is m=15kg

The speed is u=9ms^-1

The acceleration is a=3ms^-2

The coefficient of kinetic friction is

mu_k=F_r/N=4

The normal force is N=15gN

The frictional force is F_r=mu_k xx N=4*15g=60gN

The force necessary to accelerate the object is =FN

The acceleration due to gravity is g=9.8ms^-2

According to Newton's Second Law

F-F_r=ma

F=ma+F_r=((15xx3)+(60g))N=633N

"Power"="Force"xx "velocity"

The power is

P=Fxxv=633*9=5697W