Work Energy And Power Question 282

Question: A block of mass m=1kg is moving with a constant acceleration a=1m/s2 on a rough horizontal plane. The coefficient of friction between the block and plane is u=0.1 . The initial velocity of block is zero at t=0 . The power delivered by the external agent at a time t = 2 sec from the beginning is equal to (Takeg=10m/s2)

Options:

A) 1 watt

B) 2 watt

C) 3 watt

D) 4 watt

Show Answer

Answer:

Correct Answer: D

Solution:

[d] m=1kg,a=1m/s2

μ=0.1

f=μmg=0.1×1×10=1N

Fext=ma+f   Fext=1+l=2N

v=u+at=0+1×2=2m/sec.
  P=Fextv=2×2=4watt.



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