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lidiya [134]
3 years ago
6

A person holding a 30 kg box 1 m above the floor puts it down. How much work was done ? Remember , the force of an objects weigh

t = mass times gravity
A. 0.0j

B. 30j

C. 147 j

D. 294 j
Physics
2 answers:
IrinaK [193]3 years ago
4 0
Hey friend! The answer is D. 294 j
frosja888 [35]3 years ago
3 0
As long as the box was 1m off the floor. it's potential energy was m•g•h = 30•9.8 = 294 joules. When the person stopped restraining the box and allowed it to move, gravity did 294 joules of work on the box, and would have done more if the floor hadn't been in the way. The person did no work on the box.
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A gun fires a bullet vertically into a 1.40-kg block of wood at rest on a thin horizontal sheet. If the bullet has a mass of 22.
Bogdan [553]

Answer:

A. 1.172 metres

B. 6.82 Ns

C. 4.796 m/s

Explanation:

The total initial momentum is gotten by multiplying the mass and initial velocity of the both bodies.

The 1.40 kg block is at rest so velocity is zero and has no momentum.

The bullet of mass 22 g = 0.022 kg with velocity of 310 m/s

Momentum = 310*0.022

Momentum = 6.82 Ns.

If the bullet gets embedded they will both have common velocity v

6.82 = (0.022+1.40)v

6.82 = 1.422v

V = 6.82/1.422

V = 4.796 m/s

How high the block will rise after the bullet is embedded is given by

H = (U²Sin²tita)/2g

Where tita is 90°

H = (4.796² * sin²(90))/(2*9.81)

H =( 23.001616*1)/19.62

H = 1.172 metres

6 0
4 years ago
A baseball diamond is a square (don’t be fooled that it is usually shown rotated by 45°). Each side of the square is 90 feet lon
gayaneshka [121]

A line from second to home creates a right triangle with 45 degree angles.

This makes the diagonal line the side length of the square multiplied by the sqrt(2)

Second to home = 90sqrt(2) = 127.279 feet ( round answer as needed)

8 0
3 years ago
Using the statistical definition of entropy, what is the entropy of a system where W = 4?
Oliga [24]
     <span> S = k ln(W)
= 1.38*10^-23 J/K * ln(4)
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4 years ago
Bone with a latticework structure is called
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3 years ago
One violin creates a sound whose intensity level is 60dB. Find the intensity level of 16 violins, each playing at this intensity
Yanka [14]

Answer:

72.04 dB.

Explanation:

The intensity level of 60dB corresponds to the sound intensity I given by the equation

60dB = 10log(\dfrac{I}{I_0} )

where I_0 = 1*10^{-12}W/m^2

solving for I we get:

6 = log(\dfrac{I}{I_0} )

10^6 =\dfrac{I}{1*10^{-12}}

\boxed{I = 1*10^{-6} W/m^2}

Now, when 16 violins are playing the intensity I becomes

{I = 16(1*10^{-6} W/m^2)

which on the decibel scale gives

dB = 10log(\dfrac{16*10^{-6}}{1*10^{-12}} )

dB = 72.04\: dB.

Thus, playing 16 violins together gives the intensity level of 72 dB.

8 0
3 years ago
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