work and the joule Flashcards

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1
Q

Define work done

A

The work done, is the product of the force and the distance moved by the force in the direction of movement.

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2
Q

What is the equations of work done

A

w = f x s

power x time = work done

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3
Q

what is the link between energy transferred and work done

A

they are the same

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4
Q

is work a vector or scalar quantity and why

A

its a scalar quantity because it has a magnitude but no direction.

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5
Q

what can work done be though of as

A

amount of energy transferred from one form to another

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6
Q

a man pushes a shopping trolley with a horizontal force of 28N, moving a distance of 12m.

A) how much work did he do on the trolley if there was no friction

B) How much work did he do on the trolley if the frictional force was 8N

C) what is the meaning of the subtraction of the work done in part a and b.

A

A) 336J

B) 240J

c) 96J was done in overcoming the frictional forces and this work was not done on the trolley

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7
Q

what is the SI unit of work done

A

J ie.joule

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8
Q

What is the equivalent of 1 joule in newton terms

A

Newtonmetre

Nm

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9
Q

For vertical motion what is the significance of Force (F)
in the equation

W = FS

A

F = mg

force here is the weight of the object

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10
Q

an object of mass 34kg is raised from the ground to a shelf 7.5 metres above the ground. How much work has been done?

GIVE STEPS

A

W= fs
W= mg x distance in direction of force

W = 34g x 7.5

W= 2500J

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11
Q

what is the equation for work done when force applied at an angle

A

w = Fs Cos theta

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