Question

26. A man exerts a 80 N force on a load of mass 6 kg along a rough surface. The frictional force acting on the load is 20 N. mass = 6 kg 20 N 80 N 5 m Given that the mass moves 5 m horizontally in 30 s, what is the useful power developed by the man? (a) 10 W (b) 13 W (c) 78 W (d) 300 W
pls
tell me the ans with explanation ​

Answer 1

❥︎ANSWER

If body is moving on rough surface 

Frictional force = (fs)max=fk=μmg=0.6×10×10=60N

Since friction is self adjusting force maximum forc eof 60N is acting, but here only External force = 20N  is acting so friction can acts is 20N

If external force increases then f will increase and go upto 60N beyond which object will move

❥︎THANKS

I hope it will help you.

Answer 2

Answer:

10 watt

explanation

here net force = 60 N (80 - 20= 60N)

as we know that

w=F×s

w = 60 × 5 = 300J ( given displacement 5m)

now power = W/T

P = 300/30 = 10 Watt ( given time = 30 sec)