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
Answer:
The final velocity of the car is 36 m/s.
Explanation:
Given;
initial velocity of the car, u = 20 m/s
time of the car acceleration, t = 4 s
acceleration of the car, a = 4 m/s²
the final velocity of the car is calculated as;
v = u + at
where;
v is the final velocity of the car
v = 20 + (4 x 4)
v = 36 m/s
Therefore, the final velocity of the car is 36 m/s.
You have three known variables:
Acceleration -

Time -

Initial Velocity -

For the first part of your question:

For the second part of your question:

This still needs to be converted to m/h:
Answer:
The average net force on the truck is 375 Newtons.
Explanation:
Using Newton's 3rd equation of motion, we have :
×a×s
where, v = final velocity = 25 m/s
u = initial velocity = 20 m/s
a = acceleration
s = distance traveled = 300 m
Using these values in the above equation, we get acceleration = 0.375 m/
Using Newton's second law, we have:
F=m×a
where m = mass = 1000 kg
a= acceleration = 0.375 m/
Putting values we have F=375 N