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mel-nik [20]
4 years ago
6

A construction worker dropped a brick from a high scaffolding. How fast was? a. How fast was the brick moving after 4.0 s of fal

ling? b. How far did the brick fall after 4.0 s of falling?
Physics
1 answer:
Zigmanuir [339]4 years ago
5 0
A) How fast was the brick moving after 4s?
Vf=?
Vi=0 (because it was dropped, not thrown)
A= -9.8m/s^2 (gravity)
t= 4s
Use the equation Vf=Vi+A(t)
Vf=0+(-9.8)(4)
Final answer: Vf= -39.2m/s
b) How far did the brick fall after 4s?
D=?
Vi=0
t=4s
A=-9.8m/s2
**You do have the final velocity, but it is best to avoid using numbers that you have calculated yourself.**
Use the equation: d=Vi(t)+0.5(A)(t)^2
d=(0)(4)+0.5(-9.8)(4)^2
d=(-4.9)(16)
d=-78.4m
Therefore, after 4s the brick fell 78.4m
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(b) The temperature

(i) Effect of colour of light: The critical angle for a pair of media is less for the violet light and more for the red light. Thus the critical angle increases with the increase in wavelength of light.

(ii) Effect of temperature: The critical angle increases with increase in temperature because on increasing temperature of medium, its refractive index decreases.

According to the question,

μ 1​ sinCR​ =1

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μ 1​ > μ 2​  and μ 2​ > μ 3

⟹μ 1​ > μ 2​ > μ 3

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The critical angle increases with the increase in wavelength of light.

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7 0
2 years ago
calculate the momentum of 5.07 kg egg that is dropped from a roof and falls 2 seconds before hitting the ground.
inysia [295]
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The egg's momentum is   (5.07 kg) x (19.6 m/s) = 99.4 kg-m/s .
8 0
3 years ago
After a model rocket reached its maximum height, it then took 5.0 seconds to return to the launch site. what is the approximate
kifflom [539]
Air resistance is ignored.
g = 9.8 m/s².
At maximum height, the vertical velocity is zero.

Let h =  the maximum height reached.
Let u =  the vertical launch velocity.

Because ot takes 5.0 seconds to reach maximum height, therefore
(u m/s) - (9.8 m/s²)*(5 s) = 0 
u = 49 m/s

The maximum height reached is
h = (49 m/s)*(5 s) - (1/2)*(9.8 m/s²)*(5 s)²
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Answer: 122.5 m
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3 years ago
PHYSICS PLEASE HELP
WINSTONCH [101]

Explanation:

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Newton was the first to see that such apparently diverse phenomena as a satellite moving near the Earth's surface and the planets orbiting the Sun operate by the same principle: Force equals mass multiplied by acceleration, or F=ma.

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7 0
3 years ago
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What is the purpose of the scapula to move during arm elevation?
Inessa [10]

The purpose of the scapula to move during arm elevation is increase the range of elevation of the arm.

<h3>What is the importance of movement of the scapula during arm elevation?</h3>

The scapula is an important bone which is found in the shoulder and back region of the body.

The scapula enables and increases the range of motion of the arm with its motions.

During arm elevation, the scapula undergoes an upward rotational motion.

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2 years ago
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