Person X pushes twice as hard against a stationary brick wall as person Y. Which one of the following statements is correct?
1 answer:
Answer:
D) Both do zero work
Explanation:
The work done by a force is given by:
where
F is the force applied
d is the displacement
is the angle between the direction of the force and the displacement
From the formula, we notice that work is done online when the displacement is non-zero, so when the object is moving.
In this problem, the wall is stationary: this means that the displacement is zero, d = 0, so no work is done.
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I attached the missing picture.
We can figure this one out using the law of conservation of energy.
At point A the car would have potential energy and kinetic energy.
Then, while the car is traveling down the track it loses some of its initial energy due to friction:
So, we know that the car is approaching the point B with the following amount of energy:
The law of conservation of energy tells us that this energy must the same as the energy at point B.
The energy at point B is the sum of car's kinetic and potential energy:
As said before this energy must be the same as the energy of a car approaching the loop:
Now we solve the equation for
:
We can figure this one out using the law of conservation of energy.
At point A the car would have potential energy and kinetic energy.
Then, while the car is traveling down the track it loses some of its initial energy due to friction:
So, we know that the car is approaching the point B with the following amount of energy:
The law of conservation of energy tells us that this energy must the same as the energy at point B.
The energy at point B is the sum of car's kinetic and potential energy:
As said before this energy must be the same as the energy of a car approaching the loop:
Now we solve the equation for