Answer:
Step-by-step explanation:
a. Work is done when the direction of the force and the distance is parallel, that is in the same direction. So, the distance here has both a horizontal and vertical component. This is because when a plane takes off, it doesn't just shoot upward, but move along the surface and increase its height from the ground.
So now, we know that the direction of the force upward (since it's a thrust). That's why work is done only when you take the vertical component of your direction(distance). Because force and distance must be parallel.
b. Yes. Kinetic energy(K.E) is directly proportional to velocity(speed).
And velocity changes from take off to landing. So there is a change in kinetic energy.
c. Gravitational potential energy(GPE) is directly proportional to height. So when height increases, it will increase too. After take off, there will be an increase of height.
d. Mechanical energy is the sum of potential and kinetic energy. As both K.E and GPE change when the values of velocity and height respectively varies, so will the mechanical energy.