Oxygen makes up more than 90 percent of the volume of the Earth's crust. Is oxygen found as a solid, liquid, or gas?
1 answer:
You might be interested in
Answer:
-4892 J
Explanation:
The work done by friction is equal to the difference in mechanical energy of the car between the bottom of the loop (point A) and the top of the loop (point B).
The mechanical energy of the car at point A is
where
is the mass of the car
is the speed at point A
is the height of the car at point A (zero because it is at the bottom of the loop)
Substituting into the equation, we find
The mechanical energy of the car at point B is
where
is the mass of the car
is the speed at point B
(twice the radius) is the height of the car at point B, at the top of the loop
Substituting into the equation, we find
So, the work done by friction is
And the work is negative because it is done against the motion of the car.