Answer : The correct option is, (D) A machine does 400 joules of work in 5 seconds.
Explanation :
Power : It is defined a the rate of doing work per unit time.
Formula used :

where,
P = power
w = work done
t = time
Now we have to determine the rate of power for the following options.
(A) A machine does 200 joules of work in 10 seconds.

(B) A machine does 400 joules of work in 10 seconds.

(C) A machine does 200 joules of work in 5 seconds.

(D) A machine does 400 joules of work in 5 seconds.

From this we conclude that, a machine does 400 joules of work in 5 seconds has the highest rate of power.
Hence, the correct option is, (D)
Answer:
more speed means that an object has more energy, now if an object's place is something such as a hill, the potential energy will increase meaning an object will have more speed and acceleration. this is because you have the earth's gravity helping you out when the object goes downhill, giving it the higher potential energy
There is an indirect relationship between length and frequency. The longer the length the pipe has, the higher frequency it is. The shorter the length the pipe has, the lower frequency it is.
<u>Explanation:</u>
The four properties of the string that affect its frequency are length, diameter, tension, and density. These properties are described below: When the length of a string is changed, it will vibrate with a different frequency. Shorter strings have higher frequency and therefore higher pitch.
The longer the tube is the lower the pitch of the note that it can emit. When a tube is heated it expands and so is longer! As the gas in the tube gets warmer the molecules move faster, that means they can carry the vibrations of the sound wave more rapidly and so the pitch goes up.
D.) Distance travelled / time ...........