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3 years ago

•Would a moving fan have energy? Why or why not.

Physics

1 answer:

Pepsi [2]3 years ago

7 0

Moving fan has rotational kinetic energy
Non moving fan has no energy since it is in rest

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Two astronauts (each with mass 100 kg) are drifting together through space. They are connected to each other by a rope 5 m in le

Nana76 [90]

Answer:

1000 kgm²/s, 400 J

1000 kgm²/s, 1000 J

600 J

Explanation:

m = Mass of astronauts = 100 kg

d = Diameter

r = Radius = $\frac{d}{2}$

v = Velocity of astronauts = 2 m/s

Angular momentum of the system is given by

$L=mvr+mvr\\\Rightarrow L=2mvr\\\Rightarrow L=2\times 100\times 2\times 2.5\\\Rightarrow L=1000\ kgm^2/s$

The angular momentum of the system is 1000 kgm²/s

Rotational energy is given by

$K=I\omega^2\\\Rightarrow K=\frac{1}{2}(mr^2)\left(\frac{v}{r}\right)^2\\\Rightarrow K=mv^2\\\Rightarrow K=100\times 2^2\\\Rightarrow K=400\ J$

The rotational energy of the system is 400 J

There no external toque present so the initial and final angular momentum will be equal to the initial angular momentum 1000 kgm²/s

$L_i=L_f\\\Rightarrow 2mv_ir_i=2mv_fr_f\\\Rightarrow v_f=\frac{v_ir_i}{r_f}\\\Rightarrow v_f=\frac{2\times 2.5}{0.5}\\\Rightarrow v_f=10\ m/s$

Energy

$E_2=mv_f^2\\\Rightarrow E_2=100\times 10\\\Rightarrow E_2=1000\ J$

The new energy will be 1000 J

Work done will be the change in the kinetic energy

$W=E_2-E\\\Rightarrow W=1000-400\\\Rightarrow W=600\ J$

The work done is 600 J

5 0

3 years ago

A train travels 190km in 3.0 hours and then 120 km in 2.0 hours. What is it’s average speed ?

xxMikexx [17]

Answer:

60 km/h

Explanation:

Simplify the speed:

120÷2=60

Hence, the average speed is 60 km/h.

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2 years ago

A 10-meter rope is lying on the floor and has a mass force of 20 N. How much work is required to raise one end of the rope to a

VMariaS [17]

Answer:10N

Explanation: I think

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3 years ago

a bends each wavelength of white light slightly differently so that each wavelength color comes out separated forming a rainbow

lianna [129]

The answer here is prism. The light passing through prism experiences bending of its multiple wavelength composition which allows it to visibly shows the difference in each of the light's color wavelength, violet bending the most while the least is the color red.

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3 years ago

Describe the differences among ultraviolet waves, visible light waves, and infrared waves. how are these waves alike?

sergeinik [125]

Our eyes are detectors which are designed to detect visible light waves (or visible radiation). ... The electromagnetic spectrum includes gamma rays, X-rays, ultraviolet, visible, infrared, microwaves, and radio waves. The only difference between these different types of radiation is their wavelength or frequency.

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3 years ago