Answer: B
Explanation:the voltage is just like the force that drives the current through out the circui... When trippled, the force increases and the current increases since the resistance in the circuit remains constant.
Answer:
13.41 horsepower
Explanation:
Power: This can be defined as the rate at which energy is used up by a body. The S.I unit of power is Watt (W).
The expression for power is given as,
P = Ek/t...................... Equation 1
Where P = power, Ek = Kinetic Energy of the car, t = time.
Recall that,
Ek = 1/2mΔv²............ Equation 2
Where m = mass of the car, Δv = change in velocity of the car.
Substitute equation 2 into equation 1
P = 1/2(mΔv²)/t...................... Equation 3
Given:m = 1000 kg, Δv = 30-20 = 10 m/s, t = 5 s
Substitute into equation 3
P = 1/2(1000×10²)/5
P = 10000 W.
If,
745.7 W = 1 hp,
Then,
10000 W = (10000/745.7) hp
= 13.41 hp.
P = 13.41 horsepower
For a cylinder that has both ends open resonant frequency is given by the following formula:

Where n is the resonance node, v is the speed of sound in air and L is the length of a cylinder.
The fundamental frequency is simply the lowest resonant frequency.
We find it by plugging in n=1:

To find what harmonic has to be excited so that it resonates at f>20Hz we simply plug in f=20 Hz and find our n:

We can see that any resonant frequency is simply a multiple of a base frequency.
Let us find which harmonic resonates with the frequency 20 Hz:

Since n has to be an integer, final answer would be 323.