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Brut [27]
3 years ago
13

A student does 25 J of work on the handle of a pencil sharpener. If the pencil sharpener does 20 J of work on the pencil, what i

s the efficiency of the sharpener?
Physics
1 answer:
allsm [11]3 years ago
3 0

Answer:

80%

Explanation:

Efficiency of machine = work output/work input  ×100 %

From question, work output = 20J

Work input = 25J.

Therefore efficiency = 20/25 × 100 %

Efficiency = 20×4 %

Efficiency = 80%

I hope this was helpful, please mark as brainliest

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They are positive and remain inside the nucleus.
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2 years ago
A 0.5-kilogram apple falls from a height of 2 meters to 1.50 meters. Ignoring frictional effects, what is the kinetic energy of
spin [16.1K]

The  final kinetic energy of the ball is 2.45 J

Explanation:

We can solve this problem by using the law of conservation of energy.

In absence of frictional effect, the mechanical energy of the apple must be conserved during the fall. So we can write:

U_i +K_i = U_f + K_f

where :

U_i is the initial potential energy, at the top

K_i is the initial kinetic energy, at the top

U_f is the final potential energy, at the bottom

K_f is the final kinetic energy, at the bottom

By explicing the potential energy, we can rewrite the equation as:

mgh_i + K_i = mgh_f + K_f

where:

m = 0.5 kg is the mass of the apple

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

h_i = 2 m is the initial height

h_f=1.50 m is the final height

The initial kinetic energy is zero, since the ball starts from rest:

K_i = 0

Therefore we can solve the equation for K_f, the final kinetic energy of the ball:

K_f = mg(h_i-h_f)=(0.5)(9.8)(2-1.50)=2.45 J

Learn more about kinetic energy and potential energy:

brainly.com/question/6536722

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#LearnwithBrainly

3 0
3 years ago
Read 2 more answers
The acceleration due to gravity on Mars is less than that on Earth. On Mars, a person will weigh than on Earth.
pantera1 [17]
On mars people would way less. 
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4 0
3 years ago
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Explain why the speed of light is lower than<br> 3.0 x 108 m/s as it goes through different media.
jekas [21]

Answer:

Sample Response: In a vacuum, there are no atoms or particles that interfere with the path of light. However, in other media, the speed of light is lower than 3.0 × 108 m/s because the wave is continuously absorbed and re-emitted by each atom in its path. The differences in speed are due to the composition of the medium and the density of the particles in the medium.

Explanation:

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3 years ago
SOMEONE HELP PLEASE :)What types of forces might be involved in Transform Boundaries?
LekaFEV [45]

Explanation:

Convergent boundaries (where plates collide) and divergent boundaries (where plates split apart).

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