If your ever high up on a roof, flat or angled, you’ll find small stones up there, sometimes thousands or millions of them..Ive made roofs before and when i go up to do any repairs etc years later, you can almost guarantee youll find lots of rocks up there,even when theres no source for small stones nearby!
Is it the rain or wind carrying them? or maybe something else?
Its puzzled me for years.

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Thanks for visiting guys.. I really need help… i’m having some issues solving the following problems… can someone help me out? I’d like to find out the following…

Can someone describe to me a situation in which a force is applied but no work is done?

(Something i’ve always wondered).. how is work and energy related?

In which on the following is work being done?
A)A person shovels snow off a sidewalk.
B)A worker lifts bricks, one at a time, from the ground to the back of a truck.
C)A roofer’s assistant carries a bundle of shingles across a construction site.

EEEEP!… find the force a person exerts in pulling a wagon 20 m if 1,500 J of work is done.

A car’s engine produces 100kW of power. How much work does the engine do in 5 s? I don’t really understand.

A color TV uses 120 W of power. How much energy does the TV use in 1 hour?

-Thanks In Advance!

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A roofer is dragging a 15.0-kg bundle of shingles up the roof using a light rope parallel to the roof. The roof is sloped at an angle of 30.0° with the horizontal.
a.Draw a free-body diagram of the forces involved.

b.What is the force component perpendicular to the roof of the weight of the bundle of shingles?

I drew the diagram, but I really don’t understand what part b is asking me for… Do they want me to state “the perpendicular force”? do they want a value? what do they want??

THANKS!

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I’M HAVING A HARD TIME WITH THE FOLLOWING!! PLEASE HELP!

Can someone explain how the scientific defenition of work is different from the everyday meaning?

Can someone give me an example of a situation in which a force is applied but no work is done?

Which of the following situations is work being done?
A)A person shovels snow off a sidewalk.
B)A worker lifits bricks, one at a time, from the ground to the back of a truck.
C)A roofer’s assistant carries a bundle of shingles across a construction site.

Can someone describe to me the circumstances for which the output work would equal the input work in a machine?

How does lubricating a machine effect the output force exerted by the machine?

I’m having a hard time calculating the mechanical advantage of a hammer if the input force is 125 N and the output force is 2,000 N.

-THANKS IN ADVANCE!!!!

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