Answer:
F = 51.3°
Explanation:
The component of weight parallel to the inclined plane must be responsible for the rolling back motion of the car. Hence, the force required to be applied by the child must also be equal to that component of weight:

where,
W = Weight of Wagon = 150 N
θ = Angle of Inclinition = 20°
Therefore,

<u>F = 51.3°</u>
Explanation:
The relationship between the wavelength and the potential difference V is given by :

Putting the values of known parameters,

(a) 


(b) 


Hence, this is the required solution.
I think what’s wrong is that the paper clip isn’t connecting to the other thing on the bottom
If an object whose mass is growing keeps the same, unchanged
kinetic energy, then its motion must slow down, because
Kinetic Energy = (1/2) (mass) (speed)² .