Answer:
W = 1250 J = 1.25 KJ
Explanation:
The work done by the boy is due to the change in the position of the cement vertically. Hence, the work done in this case will be equal to the potential energy of the cement:

where,
W = Work done = ?
mg = W = weight of cement = 500 N
h = height covered = 2.5 m
Therefore,

<u>W = 1250 J = 1.25 KJ</u>
Answer:
The velocity is 40 ft/sec.
Explanation:
Given that,
Force = 3200 lb
Angle = 30°
Speed = 64 ft/s
The resistive force with magnitude proportional to the square of the speed,

Where, k = 1 lb s²/ft²
We need to calculate the velocity
Using balance equation

Put the value into the formula

Put the value of k


At terminal velocity 
So, 


Hence, The velocity is 40 ft/sec.
Answer:
33333.35 kg
Explanation:
I got it right on Acellus, rounded to 33300 sigfigs
C is the right image for that biological process.
Water because the light is able to enter the water and allow heat to enter faster.