The pulley is really a wheel and axle with a rope or chain attached. A pulley makes work seem easier because it changes the direction of motion to work with gravity. Let's say you have to lift a heavy load, like a bale of hay, up to the second floor of a barn. You could tie a rope to the bale of hay, stand on the second floor, and pull it straight up. Or you could put a pulley at the second floor, stand at the first floor, and lift the bale of hay by pulling straight down. It would be the exact amount of work in either case, but the action of pulling down feels easier because you're working with the force of gravity.
A pulley really saves effort when you have more than one pulley working together. By looping a rope around two, three, or even four pulleys, you can really cut down on the effort needed to lift something. The trade-off? Well, as you increase the number of pulleys, you also increase the distance you have to pull the rope. In other words, if you use two pulleys, it takes half the effort to lift something, but you have to pull the rope twice as far. Three pulleys will result in one-third the effort — but the distance you have to pull the rope is tripled!
Answer:
Intensity = 11.56W/m²
The energy flowing through the given area is 4.55 J
Explanation:
The expression for the intensity of the electromagnetic wave is,
Here,
is the permittivity of the free space,
is the electric field amplitude and
c is the speed of the light.
substitute
⁸m/s for c
8.85×10 −12 C²
/N⋅m² for 
and 93.3 V/m for 
The expression for the energy is,
E = I×A×t
Here, I is the intensity of the electromagnetic wave,
A is the area, and
t is the time.
Substitute
11.56W/m² for I
0.0287m ² for A
13.7s for t
The energy flowing through the given area is 4.55 J
D. Soil is composed of weathered parent material where as crushed rock is not.
Answer:
125.5J
Explanation:
Given parameters:
Mass of the bowling ball = 6.1kg
Height of lifting = 2.1m
Unknown:
Increase in the ball energy = ?
Solution:
The ball has changed position by moving it from one point to another. So, it has acquired more potential energy.
Potential energy = mgh
m is the mass
g is the gravity
h is the height
Now insert the given parameters and solve;
Potential energy = 6.1 x 9.8 x 2.1 = 125.5J
