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inessss [21]
3 years ago
13

7. A girl pushes her little brother on his sled with a force of 300. N for 750. m. How much work is this if the force of frictio

n acting on the sled is (a) 200. N. (b) 300. N?​
Physics
1 answer:
victus00 [196]3 years ago
3 0

Answer:

a) 75000Joules

b) 0Joules

Explanation:

Workdone = Force * Distance

Given

distance= 750m

Force = 300N

a) If the frictional force = 200N

The Total force = 300N - 200N = 100N

Work done = 100 * 750

Workdone = 75,000Joules

Hence the workdone if the force of friction is 200N is 75,000Joules

b) If the frictional force = 300N

The Total force = 300N - 300N = 0N

Work done = 0* 750

Workdone = 0Joules

Hence the workdone if the force of friction is 300N is 0Joules i.e no work will be done on the sled

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3 years ago
A 75-kg sprinter accelerates from rest to a speed of 11.0 m/s in 5.0 s. (a) calculate the mechanical work done by the sprinter d
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The mechanical work done by the sprinter during this time will be 4537.5 J , the average power the sprinter must generate will be 907.5 W and if the sprinter converts food energy to mechanical energy with an efficiency of 25% then he will be burning calories at 54.20 calories per second.

Work in physics is the energy that is transferred to or from an item when a force is applied along a displacement. It is frequently described in its most basic form as the result of force and displacement.

The quantity of energy moved or transformed per unit of time is known as power in physics. The watt, or one joule per second, is the unit of power in the International System of Units.. A scalar quantity is power.

Given 75-kg sprinter accelerates from rest to a speed of 11.0 m/s in 5.0 s.

So let,

m = 75 kg

v = 11.0 m/s

t = 5.0 s

So the mechanical work done by the sprinter during this time will be as follow:

W = 0.5 mv²

W = 0.5 (75)(11)²

W = 4537.5 J

The average power the sprinter must generate will be as follow:

Power(P) = W / t

P =  4537.5/5

P = 907.5 W

Only 25% is absorbed. So, the sprinter only absorbed 226.875 J per second which is equal to 54.20 calories per second.

Hence   mechanical work done by the sprinter during this time will be 4537.5 J , the average power the sprinter must generate will be 907.5 W and if the sprinter converts food energy to mechanical energy with an efficiency of 25% then he will be burning calories at 54.20 calories per second.

Learn more about mechanical power here:

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1 year ago
Describe a situation when you might travel at a high velocity, but with low acceleration
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Reading a book in your warm, comfy seat ... in Row-27 of a
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A boy drags a box of toys.It experiences a frictional force of 10N .calculate acceleration of the system
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Answer:

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Explanation:

i believe that is right

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The tendency of two masses alone in the universe to drift together is a result of
torisob [31]
It is as a result of gravity.  (D)

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G = 6.673 × 10⁻¹¹ Nm²kg⁻²
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3 years ago
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