Answer:a
Explanation:
We have to lift the load two loads up one story, so energy required is
let m be the mass of each load and h is the height of each story
Energy 

Here energy gained is the potential energy which depends upon the datum(floor).
For lifting one load up one story
Energy required

thus
is half of 
So option a is correct
Explanation:
This is because the drag force suffered by the aircraft is proportional to the speed at which it travels. The thrust of the engines prints a speed to the plane and this speed prints a drag force, always reaching an equilibrium point of these two forces where the speed of the plane is constant and the acceleration is equal to zero.
Therefore, by reducing the thrust, the drag force is greater and the plane begins to decrease its speed, until it reaches the point where the new drag force is matched with the new thrust force, giving it a new final speed , without acceleration.
Answer:
M = 500 J
Explanation:
Given that,
Mass, M = 1000 g = 1 kg
Height, h = 10 m
Potential energy is given by :
P = mgh
P = 1×10×10
P = 100 J
The kinetic energy at ground = 400 J
Mechanical energy = sum of kinetic and potential energy
So,
M = 100 + 400
M = 500 J
So, the mechanical energy of the system is 500 J.
Complete Question
The complete question iws shown on the first uploaded image
Answer:
a

b

Explanation:
Now looking at the diagram let take that the magnetic field is moving in the x-axis
Now the magnetic force is mathematically represented as
x B
Note (The x is showing cross product )
Note the force(y-axis) is perpendicular to the field direction (x-axis)
Now when the loop is swinging forward
The motion of the loop is from y to z to to x to y
Now since the force is perpendicular to the motion(velocity) of the loop
Hence the force would be from z to y and back to z
and from lenze law the induce current opposes the force so the direction will be from y to z to x
Now when the loop is swinging backward
The motion of the induced current will now be x to z to y
I think the answer is c AC power source
Hope this help you?