The refrigerator in Jan\'s kitchen was moved to clean the floor. Jan is now tryi
ID: 1329783 • Letter: T
Question
The refrigerator in Jan's kitchen was moved to clean the floor. Jan is now trying to push it back into place. For each of the two situations below, is the magnitude of the force that Jan exerts on the fridge greater than, less than, or equal to the magnitude of the force exerted on Jan by the fridge? Explain your answer. Jan is pushing on the fridge but it just won't budge. Jan pushes with all her might and the fridge starts moving at a slow constant speed. . Jan's friend Sue is sitting on a stool watching Jan struggle with the fridge and says: "Hmmm, Jan... unlike living things, non-living things don't always exert forces on things they touch. Take my stool here, for instance. If I poke you with my stool, it would exert a force on you. When I am just sitting on it, it doesn't exert any force on me. Instead it acts like the floor and keeps me from falling. " Do you agree or disagree with Sue's reasoning about her stool? Explain.Explanation / Answer
Answer :
If the force exerted by Jan on the fridge is less than the force exerted by fridge on Jan then Jan should be pushed back. However, it would not happen because the fridge is not moving. The gravitational force on the fridge is more than the force applied by Jan. At the same time, the gravitational force on the Jan also needs to be considered. Hence, we could say that gravitation force on both Jan and fridge are equal. Hence, there would not be any work done on the fridge. Hence, fridge would not move.
If the force exerted by Jan on the fridge is equal to the opposite force by fridge on Jan then there would not be any work done on any object. Hence, the fridge would not budge.
If the force exerted by Jan on the fridge is more than the force exerted by fridge then the fridge would move in the forward direction. Hence, the first condition would be failed as there is a work done.
As we explained in the above question, the force applied by Jan on the fridge should be more than the gravitational force on the fridge. Hence, the fridge starts moving.
Here, we should consider that the fridge is moving at a constant speed. It means, the displacement happened on the fridge should be equal to the displacement happened on Jan. It means, Jan is also moving at the same speed w.r.t fridge.
It shows again the force exerted by fridge on Jan is equal.
Explanation for Sue’s comment :
As per Sue’s statement, the non living things would not exert force on any object.
If the stool did not exert force on Sue then Sue should fall down. However, Sue is able to sit on the stool without falling.
Living things would exert force by means of its potential energy. Sue’s potential energy was converted to kinetic energy in throwing stool on to Jan. Hence, the energy transformed to the stool from Sue is able to exert force on Jan once it hits Jan.
It clearly indicates that both living things as well as non living things would exert force on other things.
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