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3 years ago

A weightlifter lifts a 1250-N barbell 2 m in 3 s.How much power was used to lift the barbell?

Physics

1 answer:

Vlad [161]3 years ago

5 0

The power is 833.3 W

Explanation:

First of all, we need to calculate the work done in lifting the barbell, which is equal to the change in gravitational potential energy of the barbell:

$W=(mg)h$

where

mg = 1250 N is the weight of the barbell

h = 2 m is the change in height

Substituting,

$W=(1250)(2)=2500 J$

Now we can calculate the power, which is equal to the work done per unit time:

$P=\frac{W}{t}$

where

W = 2500 J is the work done

t = 3 s is the time taken

Substituting,

$P=\frac{2500}{3}=833.3 W$

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Answer:

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Explanation:

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3 years ago

Does anyone know how to solve this?

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3 years ago

A 35-mm single lens reflex (SLR) digital camera is using a lens of focal length 35.0 mm to photograph a person who is 1.80 m tal

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Answer:

a) 35.44 mm

b) 17.67 mm

Explanation:

u = Object distance = 3.6 m

v = Image distance

f = Focal length = 35 mm

$h_u$ = Object height = 1.8 m

a) Lens Equation

$\frac{1}{f}=\frac{1}{u}+\frac{1}{v}\\\Rightarrow \frac{1}{f}-\frac{1}{u}=\frac{1}{v}\\\Rightarrow \frac{1}{v}=\frac{1}{35}-\frac{1}{3600}\\\Rightarrow \frac{1}{v}=\frac{713}{25200} \\\Rightarrow v=\frac{25200}{713}=35.34\ mm$