Explanation:
The arrows that turn downwards represent energy degradation. he widths are proportional to the amount of energy in that stage. The widest of these is B

Explanation:
A. $J$ is an accepted unit of energy

B. Can be resolved thus: Work=force displacement; in terms of units, J=Nm

C. Can be resolved thus: F=ma; in terms of units, N=kg m s−2. This is a unit of force not a unit of energy and therefore the correct answer.

D. Can be resolved thus: W = Fs = mas; In terms of units, J=N m=kg m s−2 m=kg m2 s−2

Explanation:
The centripetal force on an object undergoing uniform circular motion is always towards the centre of the circle therefore the direction is different at the different locations. The magnitude of centripetal force is dependent on the radius of the circular path and the speed of the object. Since both of them are the same at both locations, the magnitude of centripetal force is constant throughout the motion. Therefore, the answer is C.

Explanation:
In order for the plane to travel from $A$ to $B$, the resultant vector of the sum of the wind vector and the vector of the orientation of the plane must point in the same direction as the vector from $A$ to $B$, as shown in the diagram below. For any of the other choices, the resultant will not be in the direction $A$ to $B$.

Explanation:
For any force, the direction is an essential aspect of the quantity. All other options here are scalar quantities.

Explanation:
Weight always acts vertically downwards

Normal reaction force is always normal (perpendicular) to the surface

In order to remain at rest, friction must act up the incline in order to keep the block from sliding down the incline under the action of the component of weight acting down the incline.

In diagram B, friction is acting down the incline. This will result in an acceleration down the incline.

In diagram C, the normal reaction is acting opposite to the weight whereas normal reaction must always be perpendicular to the contact surface.

In diagram D, weight is shown to act at an angle to the vertical, whereas weight always acts vertically downwards.

Explanation:

sin 35o=vy/2

Therefore vy=2 sin(35o)

Explanation:
Displacement is the area under the graph of velocity-time. Breaking the shape into several areas up to time 7 s:

Explanation:
The cargo starts with large negative (downward) acceleration. As the cargo container falls, it is speeding up; as it is speeding up, drag force increases, so the acceleration decreases until the cargo container reaches a terminal speed where acceleration is zero. After the parachute is opened, drag force will increase, which is greater than the weight of the cargo container, causing an opposite, upwards, acceleration (deceleration). As the cargo container slows down the drag force decreases, so the net force decreases, and acceleration decreases again until the cargo container reaches a lower terminal speed where acceleration is zero and the forces are balanced.

Explanation:
At the top of its trajectory, vertical velocity will be zero, but the horizontal velocity will be constant, therefore velocity will be horizontal.
Acceleration due to gravity is always downward

Explanation:
I is correct.
The accelerating force is always perpendicular to the direction of motion, therefore no work is done.
$W=Fs\cos (\theta )$, and $\theta$ is always 90$°$.
Also, $W=\Delta Ek$ and the speed of the object is constant so there is no change in kinetic energy.

II is incorrect.
Because velocity is a vector quantity and the direction is constantly changing, velocity is not constant.

III is correct.
Because velocity is constantly changing, the object is always accelerating.

The area underneath of the force-time graph gives the change in momentum of the box. Since the area increases with time at a constant rate, the momentum should increase at a constant rate. The only graph that satisfies this condition is the graph in A.

Therefore, the answer is A.

Alternatively, the impulse equation gives Δp=FΔt .

As $F$ is a constant, $\Delta p$ is directly proportional to $t$ and a straight line through the origin is expected.

Explanation:
Impulse = change in momentum = Ft

So the magnitude of the change in momentum = (5.1×10power3)(3.0) = 15300 $Ns$

All responses match this quantity but the number of significant figures needs to be considered. As both of the values used in the calculation have two significant figures, there should be two significant figures in the answer.

In the answer $15000Ns$, the number of significant figures is unclear. It could be 2, 3, 4 or 5. The response $15kNs$ clearly has two significant figures, so it is the best answer.

B

Explanation:

The SI unit of power is W and it is defined as Js −1 .  Additionally, power can be calculated by P = Fv When units of force and speed are substituted in the equation, the units become Nms−1 But J is the SI unit of energy. Therefore, the answer is B.

Explanation:
B is the only diagram that shows weight and tension, with the vertical component of tension equal in magnitude to the weight vector. Upwards and horizontal forces on the mass are only provided by the tension force.

The magnitude of vertical component decreases only while the projectile moves upwards. At its maximum height, the vertical component becomes zero and then starts increasing in the in the downward direction until it hits ground (making D incorrect).

Option B is obviously incorrect as moon's gravitation keeps changing the vertical component.

Explanation:
The total energy at any given instant is the sum of Ek and Ep

Explanation:
The centripetal force will act towards the centre of the circular path. In this case, it is the horizontal component of the lifting force.

This is given by $Lsin\theta$ 

Explanation:
At terminal velocity there is no accleration. Forces must be balanced, therefore the drag force is equal and opposite to the weight.

Explanation:

There are two forces acting on the pilot which are the gravitational force (weight) and the normal force of the pilot's chair.

The normal force always acts from the chair onto the person. At the top of the loop, this will act vertically downwards.

The weight is always vertically downwards.