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Salsk061 [2.6K]
3 years ago
9

A weightlifter raises a 50kg weight to a height of 2m in 2 minutes. What was the power spent by the weightlifter?

Physics
1 answer:
belka [17]3 years ago
8 0

Answer:

117.72kW

Explanation:

Given data

Mass m= 50kg

height x = 2m

time taken = 2 minutes= 129 seconds

let us find the work done

WD= force * distance

WD= mgx

WD= 50*9.81*2

WD= 981 Joules

Let us find the power

Power= work * time

Power= 981*120

Power= 117720

Power= 117.72 kW

Hence the power spent is 117.72kW

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A bird watcher meanders through the woods, walking 1.93 km due east, 1.03 km due south, and 3.84 km in a direction 52.8 ° north
Sedaia [141]

Answer:

Magnitude of displacement = 2.07 km

Magnitude of average velocity = 1.17 kmph

Explanation:

Let east represent positive x axis and north represent positive y axis.

A bird watcher meanders through the woods, walking 1.93 km due east, 1.03 km due south, and 3.84 km in a direction 52.8 ° north of west.

1.93 km due wast

           s ₁ = 1.93 i km

1.03 km due south

           s₂ = -1.03 j km

3.84 km in a direction 52.8 ° north of west

           s₃ = -3.84 cos 52.8 i + 3.84 sin 52.8 j = -2.32 i + 3.06 j km

Total displacement

          s = s ₁+  s₂+ s₃ = 1.93 i - 1.03 j -2.32 i + 3.06 j = -0.39 i + 2.03 j

  Magnitude of displacement, =\sqrt{(-0.39)^2+2.03^2}=2.07km

Time taken = 1.771 hour

Magnitude of average velocity, =\frac{2.07}{1.771}=1.17km/hr

7 0
3 years ago
What are the factor that affect the efficiency of a pulley​
alukav5142 [94]

Answer:

Tension in the chains - In a chain drive, technically, you have a closed-chain (which has no end) going around 2 pulley or gears; looking closely you have 2 parallel chains going in opposite direction. If kept in horizontal direction, the one below the other is the slack side and the other the tight side. The tension on the upper or tight side is more than the slack side. So you need to keep in mind to keep your chain drive tight so that there is no loss or rotation or lags.

Sizes of the pulley/gear - The chain will be warped around a pair of pulley or gear. The sizes of these pulley/gear will also determine the efficiency of the chain drive (consider one big and one small)

Number of pulley/gear - If the number of pulley/gear is more and chain wrapped on it with little complexity will result in decrease in efficiency because of extra tension.

Length of the chain drive - You cannot have much too long chain drive. It will make your slack side more heavy because the end are further away. You have to apply more power and possibilities of lag increases decreasing efficiency. In an ideal situation, this won't happen, but this world isn't ideal.

Friction between chains & pulley/gear - If you have studied gears (involving its teeth), you will come to know that there is friction offered on the two meeting surfaces.

Angle of contact - This would have been explained better with a diagram. Although, if you are familiar with the terms you won't have difficulty understanding. Angle of contact is the angle the chain forms with the pulley/gear at the point of contact with the center of the pulley. The angle of contact should not be too small, or else the things will be slippery.

Explanation:

8 0
3 years ago
Andre heated several solid crystals of a substance called iodine, and the iodine changed directly to a gas. The iodine gas then
Strike441 [17]

The correct choice is

B. sublimation, then condensation

Sublimation is the name of the process where a solid directly converts into gas on heating. on heating solid crystals of iodine directly change into gas. hence this is sublimation.

condensation is the process where gas is converted into liquid on cooling.

here iodine gas is being converted into droplets on reducing the temperature. hence this is condensation.


8 0
3 years ago
Read 2 more answers
Winner of five swimming gold medals at the 1988 olympics
Fed [463]
Matt Biondi..?
(I don’t know if it’s right, sorry if it is wrong)
:)
6 0
3 years ago
Why does the moon's gravity have a greater effect on the earth's ocean than the sun.
White raven [17]

Answer:

Tides on our planet are caused by the gravitational pull of the Moon and Sun. Earth's oceans "bulge out" because the Moon's gravity pulls a little harder on one side of our planet (the side closer to the Moon) than it does on the other. The Sun's gravity raises tides, too, but lunar tides are twice as big.

4 0
3 years ago
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