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3 years ago

5

When a person bends an arm a different muscle is used to bring it back to the original position. why can't the same muscle be us

ed to both bend and unbend the arm?

1 answer:

Ede4ka [16]3 years ago

8 0

Muscles can only pull not push

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A bicycle of mass m requires 50 J of work to move from rest to a final speed v. If the same amount of work is performed during t

insens350 [35]

Answer:

The final speed of the second bicycle is (v·√2)/2

Explanation:

The mass of the given bicycle = m

The amount of work required to move the bicycle from rest to speed v = 50 J

The final speed of the first bicycle = v

The mass of the second bicycle = 2m

Therefore, from conservation of energy, we have;

Work required by the first bicycle = Kinetic energy gained by the bicycle

The kinetic energy = 1/2·m·v²

∴ Energy required by the first bicycle = 50 J = 1/2·m·v²

Given that the same amount of work is performed on the second bicycle, we have;

Work performed on the second bicycle = 50 J = kinetic energy of second bicycle = 1/2·(2·m)·v₂²

Also, given that 50 J = 1/2·m·v², we have;

Work performed on the second bicycle = 50 J = 1/2·m·v²= 1/2·(2·m)·v₂²

1/2·m·v²= 1/2·(2·m)·v₂²

m·v² = 2·m·v₂²

v² = 2·v₂²

v₂ = √(v²/2) = v/√2 = (v·√2)/2

v₂ = (v·√2)/2

The final speed of the second bicycle = v₂ = (v·√2)/2.

3 0

3 years ago

At a certain point in space, there is a potential of 800 V relative to zero. What is the potential energy of the system when a +

sammy [17]

To solve this problem we will apply the concepts related to electric potential and electric potential energy. By definition we know that the electric potential is determined under the function:

$V = \frac{k_e q}{r}$

$k_e$ = Coulomb's constant

q = Charge

r = Radius

At the same time

$U = \frac{k_e q_1q_2}{r}$

The values of variables are the same, then if we replace in a single equation we have this expression,

$U = Vq$

If we replace the values, we have finally that the charge is,

$V = 800V$

$q = 1\mu C$

$U = (800V)(1*10^{-6}C)$

$U = 8*10^{-4}J$

Therefore the potential energy of the system is $8*10^{-4} J$

7 0

3 years ago

Why is it that we can see blood cells only with a microscope? A) The cells form clumps. B) The cells keep moving about. C) The c

Snezhnost [94]

D the cells are very small

7 0

3 years ago

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The dry adiabatic rate of change for unsaturated air is 10°c/1000 m. what does this mean

brilliants [131]

Adiabatic rate is used to describe the change in temperature as a result of the rising or the sinking of an air parcel.

Knowing that the dry adiabatic rate of change for unsaturated air is 10°C/1000 m means that the temperature of the unsaturated air parcel would increase (get warmer) as the air parcel sinks and will decrease (get cooler) as the air parcel rises.

Hope this helps :)

3 0

4 years ago

1) The smallest part of an element that behaves like the element is the atom.

Mandarinka [93]

Here are the answers:

1. False - Molecules is the smallest part of an element that behaves like the element.

2. False - The nucleus contains both protons and neutrons

3. True

4. True

5. A. Nucleus

6. D. Neutron

7. B. Protons and Neutrons

8. C. Electron

9. C. 6

10. C.6

5 0

4 years ago