Check your concepts!

Classical Mechanics Level 3

True or False?

  1. Work done by normal reaction force is always zero.

  2. Power dissipated by centripetal​ force is always zero.

False, False True, True True, False False, True

Harsh Shrivastava by Harsh Shrivastava , 20, India

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

1 solution

Harsh Shrivastava
Aug 25, 2016

1)Work done by Normal reaction force on a block kept in an elevator will be non-zero.

2)Since centripetel force is always directed perpendicular to the velocity, the power dissipated is F.v = F v cos ⁡ 9 0 ∘ = 0 Fv \cos 90^{\circ} = 0 .

5 Helpful 0 Interesting 0 Brilliant 0 Confused

The second statement is not always true.It is only true if we assume the particle to move in uniform circular motion.If the motion is not uniform ,then the body will acquire a non zero radial component.Thus,its motion would not be circular,and velocity would not be perpendicular to centripetal force .Therefore,P=F.v=F.v(r). Where v(r) signifies radial velocity.

A Former Brilliant Member - 4 years, 9 months ago

Log in to reply

The second statement is always correct.

Whatever be the radial component, it is always perpendicular to the velocity vector hence it cannot transfer the energy thus cannot dissipate power.

P = F.v

Also i have not assumed non-zero radial component.

Feel free to ask any doubt!

Harsh Shrivastava - 4 years, 9 months ago

Log in to reply

Nice problem!

Rishu Jaar - 4 years, 9 months ago

I am sorry but cannot understand your reasoning.

Bruno Tenorio - 4 years, 9 months ago

OK thanks for clearing my concepts.

A Former Brilliant Member - 4 years, 9 months ago

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...