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:
d = 39.7 km
Explanation:
initial position of the boat is 45 km away at an angle of 15 degree East of North
so we will have
after some time the final position of the boat is found at 30 km at 15 Degree North of East
so we have
now the displacement of the boat is given as
so the magnitude is given as
You could increase the mechanical efficiency of this screw by reducing friction along the screw threads
Answer:
a. 
b. 
It is asked for 3 quarts of water because it prevents the temperature drop.
Explanation:
Given:
- mass of frozen cheese,
- quantity of water suggested for the given cheese,
- initial temperature of cheese,
- specific heat of cheese,
- initial temperature of water,
a.
- we have specific heat of water,
so now, we use the heat equation to find the amount of heat exchange during the process:
b.
when using 1 quart of water:
It is asked for 3 quarts of water because it prevents the temperature drop.
Answer:
The pressure on each side of the clot is same.
Explanation:
The clot is moving with a constant velocity which implies that the total force on the clot is zero.
The force F is given by the formula.
F=ΔPA
where ΔP is the difference in pressure and A is the area.
Since the force is same on either side, therefore,
ΔPA=0
Also, the area is same on both side of the clot.
Therefore the difference in the pressure of both side is zero which implies that the pressure on both sides are equal.
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