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vitfil [10]
3 years ago
10

An athlete is working out in the weight room. He steadily holds 50 kilograms above his head for 10 seconds. Which statement is t

rue about this situation?
A.
The athlete isn’t doing any work because he doesn’t move the weight.
B.
The athlete isn’t doing any work because he doesn’t hold the weight long enough.
C.
The athlete is doing work because he prevents the weight from falling downward.
D.
The athlete is doing work because 50 kilograms is a significant load to lift.
Physics
1 answer:
postnew [5]3 years ago
3 0

Answer:

A. The athlete isn’t doing any work because he doesn’t move the weight.

Explanation:

We must remember the definition of work, which says that work is equal to the product of mass by the distance displaced. In this case, the athlete only does work when he lifts the weight from the ground to the point where he holds the weight suspended.

So when he's holding the weight, he doesn't do any work.

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Which galaxy type is smooth and uniform in appearance, where no new stars are forming?
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Answer: Elliptical galaxy

Explanation:

There are mainly three types of galaxies: Spiral, Elliptical and Irregular. Elliptical galaxies do not have any arms unlike spiral galaxies. The elliptical galaxies are smoother and uniform in appearance. These contain relatively old stars with any site of new star formation missing. In fact, scientists consider elliptical galaxies as those galaxies which are nearing the end of their evolution.

6 0
3 years ago
If the momentum of a 1000 kg car travelling at 10 m/s was transferred completely to a 20.0 kg traffic barrier, what would the fi
denis-greek [22]

Answer:

d. 500 m/s

Explanation:

Momentum: This is the product of the mass of a body to its velocity, The S.I unit of momentum is kgm/s.

Mathematically, momentum can be expressed as,

M = mv....................... equation 1

Where M = momentum, m = mass, v = velocity

deduced from the question,

Momentum of the car = momentum of the barrier.

MV = mv ............................. Equation 1

Where M = mass of the car, V = velocity of the car, m = mass of the barrier, v = velocity of the barrier.

making v the subject of the equation,

v = MV/m........................ Equation 2

Given: M = 1000 kg, V = 10 m/s, m = 20 kg.

Substitute into equation 2

v = 1000(10)/20

v = 500 m/s.

Hence the speed of the barrier = 500 m/s

The right option is d. 500 m/s

8 0
3 years ago
a car accelerates at a constant rate from 15 m/s to 25 m/s while it travels a distance of 125 m. How long does it take to achiev
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T=Vf-Vi/s
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2 years ago
Astronomers analyze starlight to determine a star’s (a) temperature; (b) composition; (c) motion; (d) all of the above.
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One of the characteristics of the luminous gas clouds is that they do not have direct affectation by some type of external electric or magnetic fields.

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Therefore the correct option is D

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3 years ago
Consider a car moving at a constant velocity. Recall that, for any object to move at a constant velocity, the net force acting o
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For any object to move at a constant velocity, the net force acting on the object must be ZERO.

6 0
3 years ago
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