A single reflection, like shouting at the side of a mountain and hearing
your voice come back to you, is an 'echo'.
Multiple reflection, like clapping your hands once inside a large room,
is 'reverberation'.
The "c) percent efficiency" could not be used to find the mechanical advantage of an inclined plane. There are two formulae that could be used to determine the mechanical advantage of an inclined plane which stated as MA = Length/rise and Wout=Win. MA is the mechanical advantage, Wout is the output force, Win is the input force, and "rise" is the height of the inclined plane<span>.</span>
<span>the body is moving horizontally, it doesnt matter watever kind of horizontal forces are acting.
Therefore the normal force is equal to the weight
N=mg=4.2*9.8=41N
Note: the other data in the problem have no relevance
answer
</span> the normal force on the sled is 41N
Answer: 
Explanation:
Assuming there is only force in the y-component, the total net force 
acting on the parachute and the sky diver is:
(1)
Where:
is the drag force acting upwards
is the weight of the sky diver acting downwards, hence with negative sign
Then:
(2) This is the total net force excerted on the system parachute-sky diver, and the fact it is positive means is upwards
Now, according Newton's 2nd Law of Motion the force is directly proportional to the mass 
and to the acceleration 
of a body:
(3)
Where 
is the mass of the diver.
Substituting the known values and finding :
(4)
(5)
Finally:
This is the acceleration of the sky diver. Note it has a positive sign, which means its direction is upwards.
Here, If acceleration is uniform, change is velocity will be uniform, and position-time graph represents for velocity, so it would be Linear
In short, Your Answer would be Option D
Hope this helps!
