Question

HELP!! PICTURE ATTACHED!

Answer 1

Question 17:

At point A, the snowboarder is on the point of moving and the potential energy would be at its maximum (the particle has to work against the force of gravity). The kinetic energy is zero since the snowboarder is not yet moving (has no velocity). 

Question 18:

At point C, the kinetic energy will be zero and the potential energy will be minimum. As the snowboarder moves from point C to B, there will be a transfer between the kinetic energy to the potential energy. At point B, the potential energy will be back to maximum.

Answer 2

17. At point A, the snowboarder has potential energy

Explanation:

There are two types of energy involved here:

- Gravitational potential energy: this is the energy related to the height of the snowboarder, and it is given by $U=mgh$, where m is the mass of the snowboarder, g is the gravitational acceleration and h is the height of the snowboarder relative to the ground

- Kinetic energy: this is the energy related to the motion of the snowboarder, and it is given by $K=\frac{1}{2}mv^2$, where v is the speed of the snowboarder

We see that at point A the snowboarder is located at a higher point, so h is larger, therefore he has gravitational potential energy.

18. From point C to point B, kinetic energy is converted into potential energy

Explanation:

The law of conservation of energy states that the mechanical energy (sum of potential and kinetic energy: $E=U+K$) is constant. At point C, the snowboarder is located at height h=0, so he only has kinetic energy (in fact, its speed is maximum at point C). As he moves towards point B, he increases his height: therefore, its potential energy increases, while his kinetic energy decreases (this implies that his speed decreases as well). Therefore, kinetic energy is converted into potential energy.