Hey! I empathize with you, as I just started the energy unit in physics as well!
Alright, lets list what we know, and which equation(s) we need.
PE = Gravitational Potential Energy

m = mass
g = gravity (9.8 m/s^2)
h = height
Guess what?
We need to find the height!
Lets make this more organized:
Known:
m = 40 kg
PE = 14000
g = 9.8 m/s^2
Unknown:
h = ?
================================
Now, if we take a look at the equation PEg = mgh, you will see that we have everything besides the height! So lets solve for the height by substituting in for the variables we know:
14000 J = 40 kg * (9.8 m/s^2) * h
40 * 9.8 = 392
14000 J = 392 * h
14000/392 = h
35.71 m = h
There we go! If you simply list what you know and don't know, you will find the equation you need to solve the problem.
Have a great day and good luck!
When three or more coplanar forces are acting at a point and the vector diagram closes, there is no resultant. The forces acting at the point are in equilibrium.
Answer:
The coefficient of static friction is 0.29
Explanation:
Given that,
Radius of the merry-go-round, r = 4.4 m
The operator turns on the ride and brings it up to its proper turning rate of one complete rotation every 7.7 s.
We need to find the least coefficient of static friction between the cat and the merry-go-round that will allow the cat to stay in place, without sliding. For this the centripetal force is balanced by the frictional force.

v is the speed of cat, 

So, the least coefficient of static friction between the cat and the merry-go-round is 0.29.
Answer:
The distance the car travels is 115500 m in S.I units
Explanation:
Distance d = vt where v = speed of the car and t = time taken to travel
Now v = 99 km/h. We now convert it to S.I units. So
v = 99 km/h = 99 × 1000 m/(1 × 3600 s)
v = 99000 m/3600 s
v = 27.5 m/s
The speed of the car is 27.5 m/s in S.I units
We now convert the time t = 70 minutes to seconds by multiplying it by 60.
So, t = 70 min = 70 × 60 s = 4200 s
The time taken to travel is 4200 s in S.I units
Now the distance, d = vt
d = 27.5 m/s × 4200 s
d = 115500 m
So, the distance the car travels is 115500 m in S.I units
By definition, we have that the mechanical advantage is given by the following equation:

Where,
W: is the load
T: is the tension
Substituting the values in the given equation we have:

Therefore, the mechanical advantage is equal to 5.
Answer: The mechanical advantage of this machine is: MA = 5