Answer:
12500W
Explanation:
Given parameters:
Work done = 250000J
Time taken = 20s
Unknown:
Power of the crane = ?
Solution:
Power is the defined as the rate at which work is being done;
Mathematically;
Power = 
insert the parameters and solve;
Power = 
= 12500W
I have two (2) brilliant ideas:
1). Inside the metal that the body of the car is made of, and also between the two sheets of glass that the windows are made of, install a thin layer of material that absorbs RF (radio-wave) energy . . . like the material in the glass window of your microwave oven. Then, no radio waves from the cellular base station can get INTO the car, and no radio waves from your phone can get OUT of the car. The phone can't make a connection to the cellular network, you can't make or receive calls, and you can't connect to Instagram or Brainly, so you might as well just turn it off and save your battery until next time you're outside your car.
2). Somewhere inside the car, like under the dash or in the glove box, install a teeny tiny radio receiver that can recognize the signals coming OUT of your phone. Connect it to the car's electrical system so that when it hears signals from phones inside the car, it it shuts down the car's motor so you can't start or drive. The car only works when phones inside the car are either turned off or in Airplane Mode.
My ideas are so brilliant that I really should patent them, or copyright them, or whatever you do so that other people have to pay you to use your idea. But if you want to use them, that's OK. Just go ahead. I won't mind.
part 1
mass = ρ x V
mass = 1739 kg/m³ x 3.8 km³ = 6608.2 kg
PE (potential energy)= mgh
PE = 6608.2 kg x 9.81 x 403
PE = 2.61 x 10⁷ J
part 2
megaton of TNT (Mt) =4.2 x 10¹⁵ J
convert PE to Mt:
2.61 x 10⁷ J : 4.2 x 10¹⁵ J = 6.21 x 10⁻⁹ Mt
Answer:
7.5 cm
Explanation:
In the figure we can see a sketch of the problem. We know that at the bottom of the U-shaped tube the pressure is equal in both branches. Defining 
Ethyl alcohol density and 
Glycerin density , we can write:
Simplifying:
On the other hand:
Rearranging:
Replacing (2) in (1):
Rearranging:
Data:
