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3 years ago

A weightlifter can lift 220lbs. (assume 1kg weighs 2.2lbs) If he lifts the weight 2m above the floor, how much work did he do?

1 answer:

5 0

Convert 220 lb to kg.

220/2.2 = 100kg.

W = Fd (In this case, F is the weight)
W = (100)(2)
W = 200J

P = W/t
P = (200)/(1.2)
P = 166.67W

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A block of mass m = 2.0 kg slides head on into a spring of spring constant k = 260 N/m. When the block stops, it has compressed

nasty-shy [4]

Answer:

a) Ws = 2.548 J

b) Wf = 1.153 J

c) v = 1.923 m / s

Explanation:

a) The work done by the spring force

Ws = ½ * k * x²

Ws = ½ * 260 N/m *0.14² m

Ws = 2.548J

b) The increase in thermal energy can by find using

Et = Wf

Wf = µ * m *g * x

Wf = 0.42 * 2.0 kg *9.8 m/s² * 0.14m

Wf = 1.153 J

c) The speed just as the block reaches can by fin using

EK = Ws + Et

Ek = ( 2.548 + 1.153 ) J = 3.7 J

Ek = ½ * m * v²

v² = 2* Ek / m

v = √[2 * 3.7 J / 2.0 kg]

v = 1.923 m / s

8 0

3 years ago

Providing trademark protection<br>

romanna [79]

Answer:

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5 0

3 years ago

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I'm a little bit unsure about this question.

slava [35]

Answer:

Option C. 4 Hz

Explanation:

To know the correct answer to the question given above, it is important we know the definition of frequency.

Frequency can simply be defined as the number of complete oscillations or circles made in one second.

Considering the diagram given above, the wave passes through the medium over a period of one second.

Thus, we can obtain the frequency by simply counting the numbers of complete circles made during the period.

From the diagram given above,

The number of circles = 4

Thus,

The frequency is 4 Hz

8 0

3 years ago

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There are two planets: Planet A and Planet B. Both planets are the same size but Planet B is twice the mass of Planet A. Which o

Vitek1552 [10]

Answer:

Planet B

Explanation:

The strength of the gravitational field on the surface of a planet is given by the equation:

$g=\frac{GM}{R^2}$ (1)

where:

G is the gravitational constant

M is the mass of the planet

R is the radius of the planet

In this problem, we have two planets, A and B.

The two planets have same radius, R, while they have different masses, in particular

$M_B=2M_A$

So, the mass of planet B is twice the mass of planet A.

Looking at the eq.(1), we see that the gravitational field strength is proportional to the mass of the planet: therefore, the larger the mass, the greater the field strength.

So, since planet B has larger mass, then its gravity will be stronger than planet A.

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3 years ago