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Yuki888 [10]
3 years ago
13

Suppose a vacuum cleaner uses 120 J of electrical energy. If 45 J are used to pull air into the vacuum cleaner, how efficient is

the vacuum cleaner?
Physics
1 answer:
Zigmanuir [339]3 years ago
3 0
Efficiency = 45J/120J = 0.375

Or

0.375 * 100% = 37.5 %
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What is the energy of a rock with a mass of 10.2 kg on a cliff that is 300 m height?
Anuta_ua [19.1K]

The potential energy of the rock is 30,000 J

Explanation:

The mechanical energy of an object is equal to the sum of its gravitational potential energy (PE) and its kinetic energy (KE):

E=PE+KE

where

PE is the gravitational potential energy, which is the energy possessed by the object due to its position in the gravitational field

KE is the kinetic energy, which is the energy possessed by the object due to its motion

In this problem, the rock is at rest, so its kinetic energy is zero:

KE = 0

Therefore, the energy of the rock is just equal to its potential energy, which is:

E=PE=mgh

where

m = 10.2 kg is the mass of the rock

g=9.8 m/s^2 is the acceleration of gravity

h = 300 m is the height of the rock above the ground

Substituting and solving, we find

PE=(10.2)(9.8)(300)=30,000 J

Learn more about potential energy:

brainly.com/question/1198647

brainly.com/question/10770261

#LearnwithBrainly

4 0
3 years ago
A jewellery melts 500g of Silver to pour into a mould. Calculate how much energy was released as the silver solidified.
irga5000 [103]

When silver is poured into the mould the it will solidify

In this process the phase of the Silver block will change from liquid to solid.

This phase change will lead to release in heat and this heat is known as latent heat of fusion.

The formula to find the latent heat of fusion is given as

Q = mL

here given that

m = mass = 500 g

L = 111 kJ/kg

now we can find the heat released

Q = 0.5 * 111 kJ

Q = 55.5 kJ

So it will release total heat of 55.5 kJ when it will solidify

8 0
3 years ago
What effort force will be required to lift the 20 N object using the pulley above?
Umnica [9.8K]

Answer:

I think it is 5N.

Explanation:

4 0
3 years ago
How much force is needed to accelerate a 20 kg mass at a rate of 4 m/s to the second power?
dusya [7]

Answer:

So 55 Newtons are needed.

6 0
3 years ago
Read 2 more answers
**HELP ASAP**
Tcecarenko [31]
The answer of this question is B.
5 0
3 years ago
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