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snow_tiger [21]
4 years ago
10

An 80 kg man is standing in an elevator which is moving down and slowing down at a rate of 2.0 m/s2. how hard must the floor of

the elevator push up on the man?
Physics
1 answer:
V125BC [204]4 years ago
8 0
F = mass * acceleration
F = 80kg * 2m/s^2
F = 160N
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Which range is the approximate audible range for humans?
allsm [11]

Answer:

a

Explanation:

bcz mre than that they will be affected

8 0
3 years ago
Read 2 more answers
The rms (root-mean-square) speed of a diatomic hydrogen molecule at 50∘C is 2000 m/s. Note that 1.0 mol of diatomic hydrogen at
denis-greek [22]

Answer:

A) d. (1/4)(2000m/s) = 500 m/s

B) c. 4000 J

C) f. None of the above (2149.24 m/s)

Explanation:

A)

The translational kinetic energy of a gas molecule is given as:

K.E = (3/2)KT

where,

K = Boltzman's Constant = 1.38 x 1^-23 J/K

T = Absolute Temperature

but,

K.E = (1/2) mv²

where,

v = root mean square velocity

m = mass of one mole of a gas

Comparing both equations:

(3/2)KT = (1/2) mv²

v = √(3KT)/m  _____ eqn (1)

<u>FOR HYDROGEN:</u>

v = √(3KT)/m = 2000 m/s  _____ eqn (2)

<u>FOR OXYGEN:</u>

velocity of oxygen = √(3KT)/(mass of oxygen)  

Here,

mass of 1 mole of oxygen = 16 m

velocity of oxygen = √(3KT)/(16 m)

velocity of oxygen = (1/4) √(3KT)/m

using eqn (2)

<u>velocity of oxygen = (1/4)(2000 m/s) = 500 m/s</u>

B)

K.E = (3/2)KT

Since, the temperature is constant for both gases and K is also a constant. Therefore, the K.E of both the gases will remain same.

K.E of Oxygen = K.E of Hydrogen

<u>K.E of Oxygen = 4000 J</u>

C)

using eqn (2)

At, T = 50°C = 323 k

v = √(3KT)/m = 2000 m/s

m = 3(1.38^-23 J/k)(323 k)/(2000 m/s)²

m = 3.343 x 10^-27 kg

So, now for this value of m and T = 100°C = 373 k

v = √(3)(1.38^-23 J/k)(373 k)/(3.343 x 10^-27 kg)

<u>v = 2149.24 m/s</u>

<u></u>

8 0
4 years ago
uppose that 3 J of work is needed to stretch a spring from its natural length of 30 cm to a length of 45 cm. (a) How much work i
Lesechka [4]

Answer:

(a) The work done is 0.05 J

(b) The  force will stretch the spring by 3.8 cm

Explanation:

Given;

work done in stretching the spring from 30 cm to 45 cm, W = 3 J

extension of the spring, x = 45 cm - 30 cm = 15 cm = 0.15 m

The work done is given by;

W = ¹/₂kx²

where;

k is the force constant of the spring

k = 2W / x²

k = (2 x 3) / (0.15)²

k = 266.67 N/m

(a) the extension of the spring, x = 37 cm - 35 cm = 2 cm = 0.02 m

work done is given by;

W = ¹/₂kx²

W = ¹/₂ (266.67)(0.02)²

W = 0.05 J

(b) force = 10 N

natural length L = 30 cm

F = kx

x = F / k

x = 10 / 266.67

x = 0.0375 m

x = 3.75 cm = 3.8 cm

Thus a force of 10 N will stretch the spring by 3.8 cm

7 0
4 years ago
Explain why energy is needed in active transport.
alexira [117]
Because if not it wouldn't be able to move for example if you don't eat to get the energy you need you would be weak and not be able to move as much and not be able to transport yourself to places :) hope this helps
8 0
4 years ago
How does the approximate number of atoms
Dima020 [189]
Consider the Earth as a sphere. Think of the atmosphere as having a height of say about 20000 m. The volume of a sphere is 4/3 * pi * r ^3.
Find the volume of a sphere of radius 6020000 m and subtract the volume of the Earth which is a sphere of radius 6000000 m (approx).
This would be the volume of air in m^3.

Approximate the lungs as a cube, it would be approx 0.2m x 0.2m x 0.2 m = 0.008 m^3

Divide the volume of air around the Earth by 0.008.

0.001 m^3 of air contains about 6 x 10^23 molecules which is about 12 x 10^23 atoms.

If your lungs are 0.008 m^3 then that would be about 96 x 10 ^23 or about 10^25 atoms.

Compare that number with the earlier number when dividing air in the atmosphere by 0.008.

I hope this helps. :)
7 0
4 years ago
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