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Natalka [10]
2 years ago
14

A 70 kg man's arm, including the hand, can be modeled as BIO 75-cm-long uniform rod with a mass of 3.5 kg. When the man raises b

oth his arms, from hanging down to straight up, by how much does he raise his center of mass?
Physics
1 answer:
Butoxors [25]2 years ago
7 0

Answer:

  Δy = 7.1 cm

Explanation:

The center of mass of a body is defined

            y_{cm} = 1 /M ∑m_{i}  y_{i}i

Where M is the total mass of the body, m mass of each part and ‘y’ height

Let's apply this equation to our case

We locate the reference system on the shoulders

The height of the arms is at its midpoint

            y = -75/2 = 37.5 cm

With arms down

            y_{cm} = 1/70 (63 y₀ - 3.5 37.5 - 3.5 37.5)

            y_{cm} = 1/70 (63 y)₀ - 7 37.5)

With arms up

          y_{cm}’= 1/70 (63 y₀ + 3.5 y + 3.5 y)

          y_{cm}’= 1/70 (63y₀ + 7 35.5)

let's subtract the two equations

        y_{cm}’ - y_{cm} = 1/70 2 (7 35.5)

         Δy = y_{cm}’ - y_{cm} = 2 7 35.5 / 70

         ΔY = 7.1 cm

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- farmer has recently bought a 40 acre land and wishes to fence the perimeter. given that the Land is square, what lenght of fen
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If the velocity of a proton is straight up (thumb pointing up) then RHR2 shows that the force points to the left. What would the
diamong [38]

Answer:

a) to the right

b) up

c) down

d) there will be no force on the proton

e) there will be no force on the proton

Explanation:

The complete question is

If the velocity of a proton is straight up(thumb pointing up) then RHR2 (right hand rule) shows that the force points to the left. What would the direction of the force be if the velocity were a)down, b)to the right, c)to the left, d)into the page, and e)out of the page?

The right hand rule for a positive charge states that...

Hold the thumb of the right hand at right angle to the rest of the fingers, and the rest of the fingers parallel to one another, and pointing away from the body. If the thumb shows the velocity of a positive charge in a magnetic field, and the fingers all point in the direction of the magnetic field, then the palm will push in the direction of the force on the positive charge (proton).

From this, we can deduce from the original statement about this proton that the direction of the field is into the screen of this computer. with that field direction held constant, we can work out that

a) if the thumb point down, the force will be to the right

b) if the thumb points to the right, the force will be upwards

c)  if the thumb points to the left, the force is downwards

d)  if the thumb points into the page, then there will be no force on the proton since the proton must travel perpendicularly to the magnetic field for a force to be induced on it

e) explanation is the same as foe option d.

6 0
3 years ago
Mt. Asama, Japan, is an active volcano. In 2009, an eruption threw solid volcanic rocks that landed 1 km horizontally from the c
Nata [24]

Answer:

a) 69.3 m/s

b) 18.84 s

Explanation:

Let the initial velocity = u

The vertical and horizontal components of the velocity is given by uᵧ and uₓ respectively

uᵧ = u sin 40° = 0.6428 u

uₓ = u cos 40° = 0.766 u

We're given that the horizontal distance travelled by the projectile rock (Range) = 1 km = 1000 m

The range of a projectile motion is given as

R = uₓt

where t = total time of flight

1000 = 0.766 ut

ut = 1305.5

The vertical distance travelled by the projectile rocks,

y = uᵧ t - (1/2)gt²

y = - 900 m (900 m below the crater's level)

-900 = 0.6428 ut - 4.9t²

Recall, ut = 1305.5

-900 = 0.6428(1305.5) - 4.9 t²

4.9t² = 839.1754 + 900

4.9t² = 1739.1754

t = 18.84 s

Recall again, ut = 1305.5

u = 1305.5/18.84 = 69.3 m/s

7 0
3 years ago
Four rivers have the same volume of water flow over time but fall from the different heights to power hydroelectric dams. which
sveticcg [70]

Answer:

I thibknits 175

Explanation: It's the furthest

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