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igomit [66]
3 years ago
7

A helicopter lifts a 66 kg astronaut 15 m vertically from the ocean by means of a cable. The acceleration of the astronaut is g/

11. How much work is done on the astronaut by (a) the force from the helicopter and (b) the gravitational force on her? Just before she reaches the helicopter, what are her (c) kinetic energy and (d) speed?
Physics
1 answer:
artcher [175]3 years ago
4 0

Answer

given,

mass of the astronaut = 66 kg

height of the lift = 15 m

acceleration = g/11 = 0.89 m/s²

a) the work done by helicopter

W = F× h

    = m (a+g)h

    = 66 × (9.8+0.89)15

  W =10583.1 J

b) work done by the gravity

W= mgh

W = - 66 × 9.8 × 15

W = -9702 J

c) Δ KE = net work done

  Δ KE = 10583.1 - 9702

  Δ KE = 881.1 J

d) speed

\dfrac{1}{2}mv^2 = 881.1

v = \sqrt{\dfrac{2 \times 881.1}{66}}

v =5.17 m/s

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3 years ago
A car traveling 20 m/s to the north collides with a car traveling 10 m/s to the
sergiy2304 [10]

Answer: C

Explanation:

In collision, whether elastic or inelastic collisions, momentum is always conserved. That is, the momentum before collision will be equal to the momentum after collision.

Change in momentum of the system will be momentum after collision minus total momentum before collision.

Since momentum is a vector quantity, the direction will also be considered.

Momentum = MV - mU

Let

M = 800 kg is going north

at V = 20 m/s and the other car

m= 800 kg is going south

at U = 10m/s.

Substitute all the parameters into the formula

Momentum = (800 × 20) - (800 × 10)

= 8000 kgm/s

The final momentum after collision will also be equal to 8000 kgm/s

Change in momentum = 8000 - 8000

Change in momentum = 0

5 0
3 years ago
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Compare the planets Mars and Saturn. Describe how their common characteristics are similar and Compare the planets Earth and Nep
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Question no. 1. Compare the planets Mars and Saturn. Describe how their common characteristics are similar:

Answer:  Our solar system is located in the outer spiral arm of the milky way galaxy. our solar system has one sun and nine revolving planets and . namely  

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  2. Venus
  3. Earth
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  5. Jupiter
  6. Saturn
  7. Uranus
  8. Neptune
  9. Pluto (small planet usually refer as dwarf)

Each star has its on moon/moons and has its own characteristics i.e , planet must be a celestial body , must have orbit around sun, have enough mass for self gravity, big enough to have gravity that clear its path from other same size object close to its orbit around sun.

Mars is the fourth from the sun and sixth is the Saturn from the sun in our solar system.

<u>Common in Characteristics of Mars and Saturn:</u>

  • Mars and Saturn both have celestial body.
  • Mars and Saturn both have enough mass for the gravity to get rid of rigid body forces.
  • Mars and Saturn both revolve around the sun in their own orbits.
  • Mars is the second smallest in the solar system while Saturn is second largest in the solar system.
  • Mars and Saturn both have their own moons. Mars has two while Saturn has 83 moons
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Question no. 2. Compare the planets Earth and Neptune. Describe how are they different from each other

Answer:

Earth our home planet is the third from the sun and Neptune on the other hand is the eighth from the sun in the solar system.

<u>Common differences between Earth and Neptune</u>

  • Earth is the terrestrial planet while Neptune (Ice giant) is the Jovian planet.
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  • Earth is closer to the sun and Neptune is far distant from the sun.
  • Earth consists of rocks and metals on the other hand Neptune contain gases
  • Earth is smaller than the Neptune in the solar system.
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LekaFEV [45]

Answer:

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Explanation:

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