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lorasvet [3.4K]
3 years ago
10

What type of country is described by low birth rates, lower infant mortality rates, and longer life expectancy?

Physics
1 answer:
Gala2k [10]3 years ago
8 0
For the last one should be D.
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1.A heater supplies 500kj (500,000J) over 10 minutes.
ohaa [14]
Umm... I think I saw this question somewhere else answered.... You should look for it.
4 0
3 years ago
Calculate how much work is required to launch a spacecraft of mass m from the surface of the earth (mass mE, radius RE) and plac
mylen [45]

To solve this problem it is necessary to apply the concepts related to the conservation of energy, through the balance between the work done and its respective transformation from the gravitational potential energy.

Mathematically the conservation of these two energies can be given through

W = U_f - U_i

Where,

W = Work

U_f = Final gravitational Potential energy

U_i = Initial gravitational Potential energy

When the spacecraft of mass m is on the surface of the earth then the energy possessed by it

U_i = \frac{-GMm}{R}

Where

M = mass of earth

m = Mass of spacecraft

R = Radius of earth

Let the spacecraft is now in an orbit whose attitude is R_{orbit} \approx R then the energy possessed by the spacecraft is

U_f = \frac{-GMm}{2R}

Work needed to put it in orbit is the difference between the above two

W = U_f - U_i

W = -GMm (\frac{1}{2R}-\frac{1}{R})

Therefore the work required to launch a spacecraft from the surface of the Eart andplace it ina circularlow earth orbit is

W = \frac{GMm}{2R}

3 0
3 years ago
What centripetal force is needed to keep a 7kg mass moving in a circle of 4 meters radius at 15m/s
liq [111]

Answer:

We conclude that the centripetal force needed to keep a 7kg mass moving in a circle of 4 meters radius at 15m/s is 393.75 N.

Explanation:

Given

  • Mass m = 7 kg
  • Radius r = 4 m
  • Velocity v = 15m/s

To determine

We need to determine the centripetal force needed to keep a 7kg mass moving in a circle of 4 meters radius at 15m/s.

We know a centripetal force acts on a body to keep it moving along a curved path.

We can determine the centripetal force using the formula

F_c=\frac{mv^2}{r}

where

  • m is the mass
  • v is the velocity
  • r is the radius
  • F_c is the centripetal force

substitute m = 7, r = 4, and v = 15 in the formula

F_c=\frac{mv^2}{r}

F_c=\frac{7\left(15\right)^2}{4}

F_c=\frac{1575}{4}

F_c=393.75 N

Therefore, we conclude that the centripetal force needed to keep a 7kg mass moving in a circle of 4 meters radius at 15m/s is 393.75 N.

7 0
3 years ago
a car accelerates from rest to a velocity of 5meters/second in 4 seconds. what is its average acceleration over this period of t
Pani-rosa [81]

Answer:

1.25 m/s²

Explanation:

Average acceleration is the change in velocity over change in time.

a = Δv / Δt

a = (5 m/s − 0 m/s) / 4 s

a = 1.25 m/s²

6 0
3 years ago
Electromagnetic waves can travel through a vacuum. true or false
torisob [31]

Answer:

false

Explanation:

5 0
3 years ago
Read 2 more answers
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