Answer:
- Direct current is a current in which electrons flow in one direction only
- Alternating current is a current in which the direction of the electron flow reverses periodically - so, half a cycle forward, half a cycle backward
There are several advantages of using alternating currents for the transmission of electricity across a country, over large distances. The main advantages are:
- The voltage of alternating currents can be easily increased/decreased by using transformers. For instance, a transformer is used at the beginning of the transmission line to increase the voltage (electricity is transmitted at high voltage in order to reduce dissipated power), and then another transformer is used before the electricity enters the houses, in order to decrease the voltage. Transformers only work with alternating currents.
- It is easy to interrupt the flow of an alternating current, because its value naturally becomes zero every half a cycle, so this is useful in case the current must be interrupted.
There are three forces acting on the book.
1. Force due to gravity
2. Force exerted downward by the hamster
3. Normal Force in reaction to the downward forces
Since the book is not moving, the net force is zero. The summation of all forces must be zero. Then we could find the normal force which is unknown (denoted as x).
∑F = -(4 kg)(9.81 m/s2) - 3 N + x =0
∑F = -39.24 N - 3N + x =0
x = 42 N
Therefore, the normal force is 42 N.
Answer:
Redshift, or lower power
Explanation:
doppler effect
waves get stretched when you are moving away from something, and squished when you are moving towards it. Imagine you have a long, bent wire. if you stretch out the wire, the wavelength becomes longer. This also applies to sound.
Answer:
The net force applied to the car is zero.
Explanation:
We are given that a car is moving to the left with constant velocity.
When the car moving with constant velocity
Then, the final velocity=Initial velocity
Change in velocity=Final velocity- initial velocity=0
When change in velocity is zero then , acceleration of car
When acceleration is zero then, By Newtons second law
The net force applied on the car will be zero.
Option C:The net force applied to the car is zero.
