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snow_tiger [21]

3 years ago

10

An 80 kg man is standing in an elevator which is moving down and slowing down at a rate of 2.0 m/s2. how hard must the floor of

the elevator push up on the man?

1 answer:

V125BC [204]3 years ago

8 0

F = mass * acceleration
F = 80kg * 2m/s^2
F = 160N

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What is the horse power of an electric motor which can do by 1250 joule of work in 5 seconds

Ksju [112]

1250 J in 5 sec= 250 Joule(s) per second (1250/5 0

250 Joules per second = 250 Watts ( 1J/s = 1 Watt per definition)

250 Watts output = 250/0.65 efficiency = 384 Watts input

1 Horsepower = 732 Watts

Motors 1 Horsepower and under are made in certain step sizes like

3/4 , 1/2 , 1/3, 1/4, 1/16 1/20 of a Horsepower.

3/4 Horsepower is 549 Watts

1/2 Horsepower is 366 Watts

so you need to 3/4 horsepower motor to achieve 1250 J of work in 5 seconds.

5 0

2 years ago

A force of 5 N is applied to the end of a lever that has a length

Klio2033 [76]

Answer:

The answer is 10Nm

Explanation: I ended up just messing around with the numbers, I multiplied 5 and 2 got 10 as my answer and it was right.

4 0

2 years ago

Ivan drove to the mountains last weekend. There was heavy traffic on the way there, and the trip took 7 hours. When Ivan drove h

lesya692 [45]

Answer:252 miles

Explanation:

Given

During his way to mountain it took 7 hr to drive

and during his return trip it took 4 hr to return

Let x be the distance between home and mountain

average speed for return is 27 miles per hour faster than his former trip

let v be the speed on his way to mountain thus v+27 is his return speed

thus $7=\frac{x}{v}$ ----1

for return trip

$4=\frac{x}{v+27}$ -----2

divide 1 & 2

$\frac{7}{4}=\frac{x\cdot (v+27)}{v\cdot x}$

$7v=4v+4\cdot 27$

$3v=4\cdot 27$

$v=36 mph$

thus $x=7\times 36=252\ miles$

7 0

3 years ago

What is true for ALL of the examples of electromagnetic waves? A) They all move at the same speed in a vacuum. B) They all have

gizmo_the_mogwai [7]

<em>A statement that is true for ALL of the examples of electromagnetic waves is that;</em>

A) They all move at the same speed in a vacuum

<u>The reason for qualifying 'in vacuum' is because EM waves of different frequencies often propagate at different speeds through material. Generally speaking, we say that light travels in waves, and all electromagnetic radiation travels at the same speed which is about 3.0 * 108 meters per second through a vacuum.</u>

5 0

2 years ago

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Please. Physics is so difficult.

Softa [21]

Answer:

0.010 m

Explanation:

So the equation for a pendulum period is: $y=2\pi\sqrt{\frac{L}{g}}$ where L is the length of the pendulum. In this case I'll use the approximation of pi as 3.14, and g=9.8 m\s. So given that it oscillates once every 1.99 seconds. you have the equation:

$1.99 s = 2(3.14)\sqrt{\frac{L}{9.8 m\backslash s^2}}\\$

Evaluate the multiplication in front

$1.99 s = 6.28\sqrt{\frac{L}{9.8m\backslash s^2}$

Divide both sides by 6.28

$0.317 s= \sqrt{\frac{L}{9.8 m\backslash s^2}}$

Square both sides

$0.100 s^2= \frac{L}{9.8 m\backslash s^2}$

Multiply both sides by m/s^2 (the s^2 will cancel out)

$0.984 m = L$

Now now let's find the length when it's two seconds

$2.00 s = 6.28\sqrt{\frac{L}{9.8m\backslash s^2}}$

Divide both sides by 6.28

$0.318 s = \sqrt{\frac{L}{9.8 m\backslash s^2}$

Square both sides

$0.101 s^2 = \frac{L}{9.8 m\backslash s^2}$

Multiply both sides by 9.8 m/s^2 (s^2 will cancel out)

$0.994 m = L$

So to find the difference you simply subtract

0.984 - 0.994 = 0.010 m

4 0

1 year ago

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