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3 years ago

Mary has a mass of 40 kg and sprints at 1 m/s. How much kinetic energy does she have?

Physics

1 answer:

Sav [38]3 years ago

8 0

Answer:

20 J

Explanation:

Kinetic energy is given as half of the product of mass and the square of velocity of an object:

KE = $\frac{1}{2}mv^2$

where m = mass = 40 kg

v = velocity = 1 m/s

Hence, Mary's kinetic energy is:

KE = $\frac{1}{2} * 40 * 1^2$

KE = 20 * 1 = 20 J

She has a kinetic energy of 20 J.

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$0.53m/s^2$

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4 years ago

Find the current that flows in a silicon bar of 10-μm length having a 5-μm × 4-μm cross-section and having free-electron and hol

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The current flowing in silicon bar is 2.02 $\times$ 10^-12 A.

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Length of silicon bar, l = 10 μm = 0.001 cm

Free electron density, Ne = 104 cm^3

Hole density, Nh = 1016 cm^3

μn = 1200 cm^2 / V s

μр = 500 cm^2 / V s

The total current flowing in the bar is the sum of the drift current due to the hole and the electrons.

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J = Eq (n μn + p μp)

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So, J = (V / l) q (n μn + p μp)

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J = 1012480 $\times$ 10^-16 A / m^2.

J = 1.01 $\times$ 10^-9 A / m^2

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3 years ago

A weight suspended from a spring is seen to bob up and down over a total distance of 20 centimeters twice each second.

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Answer

8. 2 Hz

9. 0.5 seconds

10. 20 cm

Explanation

Q 8

Frequency is the number of oscillation in a unit time. It is the rate at which something repeats itself in a second.

In this case, the spring bob up and down 2 times per second.

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Q 9

Period is the time taken to complete one oscillation.

2 oscillations takes 1 second

1 oscillation = 1/2 seconds.

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Amplitude is the the maximum displacement of the spring.

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