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vfiekz [6]
3 years ago
15

Any projectile always has a constant vertical acceleration of _______.

Physics
1 answer:
Mashcka [7]3 years ago
8 0

Answer:

The answer to your question is: C. -9.81 m/s²

Explanation:

A. 9.81 m/s²  acceleration is considered positive when it goes to the center of the earth, so this option is incorrect.

B. 0 m/s²  This option is incorrect because acceleration is 0 for a linear motion without acceleration.

C. -9.81 m/s²  If a projectile goes to the sky, then the acceleration will be negative.

D. It is not constant. Acceleration is constant.

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When a gas is compressed, its particles are pushed closer together so it is more dense.
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51.Shoveling snow can be extremely taxing because the arms have such a low efficiency in this activity. Suppose a person shoveli
Komok [63]

Complete question is;

Shoveling snow can be extremely taxing since the arms have such a low efficiency in this activity. Suppose a person shoveling a sidewalk metabolizes food at the rate of 800 W. (The efficiency of a person shoveling is 3%.)

(a) What is her useful power output? (b) How long will it take her to lift 3000 kg of snow 1.20 m? (This could be the amount of heavy snow on 20 m of footpath.) (c) How much waste heat transfer in kilojoules will she generate in the process?

Answer:

A) P_out = 24 W

B) t = 1470 s

C) Q = 1140.72 KJ

Explanation:

We are given;

Input Power; P_in = 800 W

Efficiency; η = 3% = 0.03

A) Formula for efficiency is;

η = P_out/P_in

Making P_out the subject, we have;

P_out = η•P_in

P_out = 0.03 × 800

P_out = 24 W

B) We know that;

Power = work done/time taken

Thus;

P_out = mgh/t

We are given;

m = 3000 kg

h = 1.20 m

Thus, time is;

t = (3000 × 9.8 × 1.2)/24

t = 1470 s

C) amount of heat wasted is calculated from;

Q = (P_in - P_out)t

Q = (800 - 24) × 1470

Q = 1,140,720 J

Q = 1140.72 KJ

3 0
2 years ago
Based on the law of conversation of energy how can we reasonably improve a machines ability to do work?
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To solve this problem we will apply the concepts related to Reyleigh's criteria. Here the resolution of the eye is defined as 1.22 times the wavelength over the diameter of the eye. Mathematically this is,

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Sin\theta = \frac{d}{L}

For small angle, sin\theta = \theta

sin \theta = \frac{d}{L}

Here,

d = Distance between lights

L = Distance from eye to lamp

For small angle sin \theta = \theta

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L = \frac{d}{sin\theta}

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