Conservation of engery and work 2.

[Ereny]

ben carries a 200N suitcase up three flights of stairs total vertical distance of 10.0m and then pushes the suitcase with a horizontal force of 50.0 N at a constant speed of 50 m s for a horizontal of 35.0 m across the 3rd floor how much work does Ben do on the suitcase during this entire motion

Total work done by Ben = mgh + F*s = 200 * 10 + 50 *35 = 2000 + 1750 = 3750 Joules.

i have a feeling this is wrong i really need help!

 

[berkeman]

ben carries a 200N suitcase up three flights of stairs total vertical distance of 10.0m and then pushes the suitcase with a horizontal force of 50.0 N at a constant speed of 50 m s for a horizontal of 35.0 m across the 3rd floor how much work does Ben do on the suitcase during this entire motion

Total work done by Ben = mgh + F*s = 200 * 10 + 50 *35 = 2000 + 1750 = 3750 Joules.

i have a feeling this is wrong i really need help!

That's close. You left out the acceleration of gravity when you plugged in the numbers.

It helps to carry units along in your equations -- if you had, you would have noticed that the units were not Joules when you calculated just mh instead of mgh.

Try again (with units this time)?

 

[Ereny]

yeah well 200 n includes the 9.81 so i don't need to include it again right?

 

[berkeman]

yeah well 200 n includes the 9.81 so i don't need to include it again right?

Whoops! You are right!

 

[Ereny]

okay so here's what i did

200N x 10m + 50 N x .5om/s = 2025

 

[Ereny]

and i think i typed the velocity wrong in the question is should be .50 m/s

 

[berkeman]

okay so here's wt i did

200N x 10m + 50 N x .5om/s = 2025

No, you had it right the first time. When pushing the object, the work is force X distance. The units of work are Newtons * meters, not Nm/s.

 

[Ereny]

ohh kk .. why did they give me the velocity then.. doesn't that mean i have to use it?

 

[berkeman]

ohh kk .. why did they give me the velocity then.. doesn't that mean i have to use it?

Nope. Not to answer the question they gave you.

 

[Ereny]

kk thanks and one more thing can you help me out too with this question https://www.physicsforums.com/showthread.php?t=595625