Power generated by a rollerblader

[TyErd]

Jacinta is rollerblading along a straight flat road at a steady speed of 15m/s. The average force of rolling friction from the wheels is around 5N and the total air resistance force is around 55N.

What is the power she is generating at this time?

 

[rock.freak667]

So what do you think you need to do to get the power?

 

[TyErd]

well there's the formula p=w/t or p=fv

 

[rock.freak667]

well there's the formula p=w/t or p=fv

If you use P=Fv, what is the force she is exerting to move at constant speed?

 

[TyErd]

how do we know net force, we only know friction

 

[rock.freak667]

how do we know net force, we only know friction

the girl is moving in a straight line at constant speed. What does Newton's 2^nd law say about her acceleration?

 

[TyErd]

so net force is 0?

 

[rock.freak667]

so net force is 0?

Yes, so what is the force she is exerting?

 

[TyErd]

um..zero?

 

[rock.freak667]

um..zero?

The force she is exerting minus the forces due to friction is zero.

 

[TyErd]

ohhh yeah! so that means she is also exerting 60N which makes her travel at constant speed! thankyou I get it now!