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SIZIF [17.4K]
3 years ago
8

50 J of work was performed in 20 seconds. How much power was used to perform this task? A. 0.4 W B. 2.5 W C. 4 W D. 24.5 W

Physics
1 answer:
Ugo [173]3 years ago
5 0

Answer:

B. 2.5 W

Explanation:

Power: This can be defined as the rate at which energy used or it i the rate at which work is done. The S.I unit of power is Watt (W).

Mathematically,

Power = Energy or work/Time

P = W/t ........................Equation 1

Where P = power used to perform the task, W = work, t = time.

Given: W = 50 J, t = 20 s.

Substitute into equation 1

P = 50/20

P = 2.5 W.

Hence the power is 2.5 W.

The right option is B. 2.5 W

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57. A red ball (m= 10 kg) is moving at 3 m/s. A green ball (m = 8 kg) is moving at 3.5 m/s. Which ball has more
Alex Ar [27]

Answer:

the green ball has 4J more energy

Explanation:

The kinetic energy is given by the formula

K = 0.5 m v^2

the kinetic energy of the red ball:

K(red) = 0.5*10*3^2= 45J

of the green ball:

K(green)=0.5*8*3.5^2 = 49J

therefore the green ball has more energy by 4 Joules

4 0
3 years ago
State the difference between viscosity and friction​
spin [16.1K]

Answer:

The main difference between friction and viscosity is that friction is used to refer to forces that resist relative motion, in general, whereas viscosity refers specifically to resistive forces that occur between layers of a fluid when fluids attempt to flow.

Explanation:

4 0
2 years ago
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A student at the top of building of height h throws one ball upward with the initial speed V and then throws a second ball downw
Vlad1618 [11]

Answer:

They are the same (assuming there is no air friction)

Explanation:

Take a look at the picture.

When the first ball (the one thrown upward) gets to the point marked as A, the speed will has the exact same value V but the velocity will now point downward (just like the second ball).

So if you think about it, the first ball, from point A to the ground, will behave exactly like the second ball (same initial speed, same height).

That is why the speeds will be the same when they reach the ground.

7 0
2 years ago
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How much energy is stored in the electric field of a 50-μm-diameter cell with a 7.0-nm-thick cell wall whose dielectric constant
Anastaziya [24]
:<span>  </span><span>Under the assumption that a cell is made up of two concentric spheres you find the surface are of the inside sphere which will be your A. 

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3 0
3 years ago
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A Car with drives into a solid object with 70 km/h, from which height would it fall if it was in free fall?​
Ilya [14]

Answer:

18.9 m.

Explanation:

From the question given above, the following data were obtained:

Initial velocity (u) = 0 m/s

Final velocity (v) = 70 km/h

Height (h) =?

Next, we shall convert 70 km/h to m/s. This can be obtained as follow:

3.6 km/h = 1 m/s

Therefore,

70 km/h = 70 km/h × 1 m/s / 3.6 km/h

70 km/h = 19.44 m/s

Finally, we shall determine the height. This can be obtained as follow:

Initial velocity (u) = 0 m/s

Final velocity (v) = 19.44 m/s

Acceleration due to gravity (g) = 10 m/s²

Height (h) =?

v² = u² + 2gh

19.44² = 0² + (2 × 10 × h)

377.9136 = 0 + 20h

377.9136 = 20h

Divide both side by 20

h = 377.9136 / 20

h = 18.9 m

Thus, the car will fall from a height of 18.9 m

8 0
2 years ago
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