A person carries a plank of wood 2 m long with one hand pushing down on it at one end with a force F1 and the other hand holding
it up at 50 cm from the end of the plank with force F2 . If the plank has a mass of 20 kg and its center of gravity is at the middle of the plank, what are the magnitudes of the forces F1 and F2 ?
1 answer:
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The amount of work done by two boys who apply 200 N of force in an unsuccessful attempt to move a stalled car is 0.
Answer: Option B
<u>Explanation: </u>
Work done is the measure of work done by someone to push an object from its present position. We can also define work done as the amount of forces needed to move an object from its present position to another position. So the amount of work done is directly proportionate to the product of forces acting on the object and the displacement of the object.
So in this present case, as the two boys have done an unsuccessful attempts to push a stalled car so that means the displacement of the car is zero as there is no change in the position of the car. But they have applied a force of 200 N each. So the amount of work done will be
Thus, the amount of work done by two boys will be zero due to their unsuccessful attempt to move a stalled car.
Answer: The energy absorbed by the reaction from the water is 996 Joules.
Explanation:
Energy absorbed by the reaction or energy lost by the water to the reaction,Q.
Mass of the the reaction ,m = 60 g
Specific heat of water = c = 4.15 J\g ^oC
Change is temperature=
Negative sigh indicates that energy was given by the water to the reaction.
The energy absorbed by the reaction from the water is 996 Joules.