Work Energy And Power Question 282
Question: A block of mass $ m=1kg $ is moving with a constant acceleration $ a=1m/s^{2} $ 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/s^{2} ) $
Options:
A) 1 watt
B) 2 watt
C) 3 watt
D) 4 watt
Show Answer
Answer:
Correct Answer: D
Solution:
[d] $ m= 1 kg, a = 1 m/s^{2} $
$ \mu =0.1 $
$ f=\mu mg=0.1\times 1\times 10=1N $
$ {F _{ext}}=ma+f~~~F _{ext}=1+l=2N $
$ v=u +at=0+1\times 2=2m/sec. $
$ \therefore ~~P=F _{ext}v=2\times 2=4watt. $
