Answer:
x_total = (A + B) cos (wt + Ф)
we have the sum of the two waves in a phase movement
Explanation:
In this case we can see that the first boy Max when he enters the trampoline and jumps creates a harmonic movement, with a given frequency. When the second boy Jimmy enters the trampoline and begins to jump he also creates a harmonic movement. If the frequency of the two movements is the same and they are in phase we have a resonant process, where the amplitude of the movement increases significantly.
Max
x₁ = A cos (wt + Ф)
Jimmy
x₂ = B cos (wt + Ф)
total movement
x_total = (A + B) cos (wt + Ф)
Therefore we have the sum of the two waves in a phase movement
F = ma
F = 85×(5-3)÷3
F = 85×(2÷3)
F = 85×0.667
F = 56.67N
There are already 2 givens, hence we can do direct substitution to get the answer. To make the process simpler, derive the distance formula from the Work formula.
Work = Force x Distance
Distance =

Work is 450J while the force is 150N hot tub
To get the proper units, get the equivalent of Joule to eliminate newton. A joule Is equal to 1 N-m
Distance =

Distance = 3m
Hence, the hot tub is lifted 3 meters.
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

: