How Is Work Calculated in a Friction Scenario with Constant Velocity?

[nbroyle1]

You are pushing a refrigerator across the floor of your kitchen. You exert a horizontal force of
291N for 7.5s, during which time the refrigerator moves a distance of 2.7m at constant velocity.

(a) What is the total work (by all forces) done on the refrigerator?

(b) What is the work done by friction?

How can I calculate the work done by friction if a mass isn't provided and there is no acceleration obviously since there is a constant velocity?

 

[tiny-tim]

welcome to pf!

hi nbroyle1! welcome to pf!

How can I calculate the work done by friction if a mass isn't provided and there is no acceleration obviously since there is a constant velocity?

that's right, the acceleration is zero and the velocity is constant …

so use the work energy theorem ​

 

[nbroyle1]

Thanks, but don't I need the mass for the work energy theorem also?

Net work=1/2mv(final)^2-1/2mv(initial)^2

 

[nbroyle1]

Is the friction force equal to the force applied since it is a constant velocity? or would that just meant that the object isn't moving at all?

 

[tiny-tim]

(try using the X² button just above the Reply box )

in this case, 1/2mv(final)²-1/2mv(initial)² = … ?

 

[nbroyle1]

doesnt it just equal zero since the velocity is the same?

 

[tiny-tim]

Is the friction force equal to the force applied since it is a constant velocity?

yes

(lots of exam questions are exactly like this)

 

[nbroyle1]

Ok awesome thanks!