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3 years ago

Astronomers believe that cosmic background radiation formed:

1 answer:

5 0

The assumption that the cosmic microwave background
is the remnant of the environment at the time of the big bang
or very shortly after it explains very well what we observe now.
So it is the current prevailing theory. "Believe" is not involved.

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a ball is thrown horizontally from the roof of a building 45.0 m tall and lands 24.0 m from the base. What was the ball´s initia

Sliva [168]

ball drops 45m under g=10m/s/s

45=1/2x10xt^2 ... application of kinematic equaion from rest

90/10=t^2

t=3

24.0 m in 3 secs => 8m/s no air resistance

4 0

3 years ago

Heat gained minus work fine is equal to what?

Zina [86]

Heat transferred - Work done = Internal Energy

Explanation:

If there is more heat transfer than the work done, the energy difference is called internal energy
The first law of thermodynamics equation is given as ΔU=Q−W where, ΔU = Internal energy; Q = Heat transfer; W = Work done
Heat = transfer of thermal energy between two bodies at different temperatures
Work = force used to transfer energy between a system and its surroundings
The First Law of Thermodynamics states - energy can be converted from one form to another with the interaction of heat, work and internal energy
Energy cannot be created nor destroyed

8 0

3 years ago

Batman (95kg) is standing on top of a 50m high building looking out over the city of Gotham. Given that he uses the potential en

Oksanka [162]

Answer:

47 kJoules (kJ)

Explanation:

Potential enegy on Earth is given by the relationship:

P.E. = mgh, where m is mass, g is the acceleration due to Earth's gravity, and h is height. Since we are given metric values, we will look for an answer that is consistent with Joules, the metric measure of energy. 1 Joule is defined as 1 kg*m^2/s^2, so we wnat units of kg, m, and sec.

We are given:

m = 95kg

h = 50 meters

Earth's gravity, g is 9.8 m/s^2

Enter the data:

P.E. = mgh

P.E. = (95kg)(9.8m/s^2)(50m)

P.E. = 46550 kg*m^2/s^2 or 46550 Joules(J)

Since we only have 2 sig figs, and since 1kJ =- 1000J

We can state the potential energy is 47kJ.

Spiderman has 47kJ of potential energy for the start of any dive back to Earth. [He needed that same amount of energy to reach that height, but we don't know from where it came. A jump, helicopter, beamed up by Scotty, or tossed up by Doctor Octopus.]

3 0

1 year ago

An inflatable raft (unoccupied) floats down a river at an approximately constant speed of 5.6 m/s. A child on a bridge, 71 m abo

saveliy_v [14]

Answer:

21.28 m

Explanation:

height, h = 71 m

velocity of raft, v = 5.6 m/s

let the time taken by the stone to reach to raft is t.

use second equation of motion for stone

$h = ut + \frac{1}{2}at^{2}$

u = 0 m/s, h = 71 m, g = 9.8 m/s^2

71 = 0 + 0.5 x 9.8 x t^2

t = 3.8 s

Horizontal distance traveled by the raft in time t

d = v x t = 5.6 x 3.8 = 21.28 m

3 0

3 years ago

Suddenly a worker picks up the bag of gravel. Use energy conservation to find the speed of the bucket after it has descended 2.3

fiasKO [112]

Explanation:

A worker picks up the bag of gravel. We need to find the speed of the bucket after it has descended 2.30 m from rest. It is case of conservation of energy. So,

$\dfrac{1}{2}mv^2=mgh\\\\v=\sqrt{2gh}$

h = 2.3 m

$v=\sqrt{2\times 9.8\times 2.3} \\\\v=6.71\ m/s$

So, the speed of the bucket after it has descended 2.30 m from rest is 6.71 m/s.

8 0

3 years ago