A) the pump removes air from the enclosure. foam absorbs vibrations from the clock
b) result is that as the air is taken out by pump, the sound of alarm reduces and eventually becomes zero. so, you cant hear the alarm ringing.
c) conclusion is that sound cant travel in vaccum and it requires a medium to travel.
An elevator has 750,000 J when it is lived 500 meters in the air
Answer: Option D
<u>Explanation:</u>
The expression to find the potential energy completely on the basis of forces that on two objects. It can be written as

Where,
m – mass of object
Acceleration due to gravity = 
h = 500 meters
Force = 1500 Newton
As we know, according to Newton second law of motion, the force can be expressed in terms of mass and gravity (F= ma). So, the potential energy can be calculated as

Hence, an elevator has 750,000 J when it is lived 500 meters in the air.
The radiations detected by Arno Penzias and Robert Wilson
were the original heat from the Big Bang.
Today, we call those waves the "Cosmic Microwave Background".
I'm not sure, but I think those guys were awarded a Nobel Prize in Physics
for that discovery.
Answer:
Explanation:
The correct answer is option C.
When the battery is operating a remote control toy the energy is converted from potential energy to the kinetic energy.
A battery stores electrical potential from the chemical reaction.
When the circuit is connected to the potential energy of the battery helps in the movement of the toy.
The energy produced by the movement of the control toy is kinetic energy.
Hence, we can say that Potential energy is changed to kinetic energy