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soldi70 [24.7K]

3 years ago

8

A machine designed to stretch a stiff spring uses 1,550 J of energy to stretch the spring. If the work output is 1,200 J, what i

s the machine’s efficiency?

1 answer:

lapo4ka [179]3 years ago

8 0

Answer:

77%

Explanation:

efficiency= work output/work input X 100%

e = 1,200j/ 1,550 j x100%

e = 1,200/1,550= 0.77

e = 0.77 x 100%

e = 77%

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A2 kg block is accelerating at the rate of 5 m/s² while being acted on by two forces. One of the forces equals 30 N, 0°. What ar

Mademuasel [1]

Answer:

20 [N], in the opposite direction of the first force.

Explanation:

We know that newton's second law stipulates that the sum of forces on a body must be equal to the product of mass by acceleration.

$SumF = m*a\\30 + F = 2*5\\F = 30 - (2*5)\\F = - 20 [N]$

The negative sign means that the other force acting on the body must be in the opposite direction to the force of 30 [N]

6 0

3 years ago

Jane has a mass of 55 kg and his body covers 700 nails with a surface area of 1.00 mm,

Oksana_A [137]

We have,

Jane mass is 55 kg
His body covered with 700 nails all of them having a surface area of 1.00 mm² each = 700 × 1 = 700 mm² = 700/1000000 = 7/10000

We know that,

Pressure = Force/Area

Let's calculate force as we already have area;

F = ma
F = 55 × 9.8 { Acceleration due to gravity }
F = 539 N

Now, if should she would be on 700 nails then pressure will be;

P = F/A
P = 539/7 × 10000
P = 5390000/7
P = 770,000 Pascal

And if should would be on a 1 nail only,

P = F/A
P = 539/1 × 1000000
P = 539000000 Pascal

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3 years ago

I MARK BRAINLIEST, PLEASE ANSWER ASAP!!! PHYSICS 20 POINTS!!

irina [24]

The first one is C. Hope this helps!! If you need anymore help just message me and I will try to get back to you quickly and help in any way i can!

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3 years ago

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Is the expression "The bigger they are, the harder they fall" a generally true statement since, in the absence of air resistance

lions [1.4K]

No, because in oxygen depraved rooms, if you drop a feather and a bowling ball at the same height and time, they will fall at the same speed and have the same amount of impact.

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Ocean waves of wavelength 26 m are moving directly toward a concrete barrier wall at 4.0 m/s . The waves reflect from the wall,

Genrish500 [490]

Answer:

a) the distance between her and the wall is 13 m

b) the period of her up-and-down motion is 6.5 s

Explanation:

Given the data in the question;

wavelength λ = 26 m

velocity v = 4.0 m/s

a) How far from the wall is she?

Now, The first antinode is formed at a distance λ/2 from the wall, since the separation distance between the person and wall is;

x = λ/2

we substitute

x = 26 m / 2

x = 13 m

Therefore, the distance between her and the wall is 13 m

b) What is the period of her up-and-down motion?

we know that the relationship between frequency, wavelength and wave speed is;

v = fλ

hence, f = v/λ

we also know that frequency is expressed as the reciprocal of the time period;

f = 1/T

Hence

1/T = v/λ

solve for T

Tv = λ

T = λ/v

we substitute

T = 26 m / 4 m/s

T = 6.5 s

Therefore, the period of her up-and-down motion is 6.5 s

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3 years ago