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Evgen [1.6K]
4 years ago
5

A ball is thrown straight upward. How does the sign of the work done by gravity while the ball is traveling upward compare with

the sign of the work done by gravity while the ball is traveling downward?A. Work done by gravity is negative while the ball is traveling upward and positive while the ball is traveling downward.B. Work done by gravity is positive while the ball is traveling both upward and downward.C. Work done by gravity is positive while the ball is traveling upward and negative while the ball is traveling downward.D. Work done by gravity is negative while the ball is traveling both upward and downward.
Physics
1 answer:
ankoles [38]4 years ago
3 0

Answer:

A.

Explanation:

  • According to the work energy theorem, the work done by external forces on a mass, must equal to the change in kinetic energy.
  • When thrown upward, the change in kinetic energy is negative, due to it must have some initial velocity, which it will diminishing while going upward, as gravity is slowing down it.
  • So, in this part of the trajectory, work done by gravity (only force acting on the ball if we neglect air resistance) must be negative.
  • In the downward part of the trajectory, as the change in kinetic energy is positive (the ball is speeding up when falling), the work done by gravity must be positive too.
  • So, the option A is the one that is true.
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A low pressure system has moved away from the equator and is moving directly over water. When the system reaches 600 N latitude,
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When the system reaches 60° North latitude after moving away from the equator and passing directly over water, it will be at a point where most of its energy is lost. 
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4 years ago
The index of refraction of silicate flint glass for red light is 1.620 and for violet light is 1.660 . A beam of white light in
Sonja [21]

Answer:

10.16 degrees

Explanation:

Apply Snells Law for both wavelenghts

\(n_{1}sin\theta_{1} = n_{2}sin\theta_{2}\)

For red

(1.620)(sin 25.5) = (1)(sin r)

For red, the angle is 35.45degrees

For violet

(1.660)(sin 25.5) = (1)(sin v)

For violet, the angle is 45.6 degrees

The difference is 45.6- 35.45 = 10.16 degrees

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3 years ago
A charge of 4.0 microC is placed at each corner of a square 0.10 m on a side.
Andre45 [30]
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3 0
3 years ago
A biologist looking through a microscope sees a bacterium at r⃗ 1=2.2i^+3.7j^−1.2k^μm(1μm=10−6m). After 6.2 s , it's at r⃗ 2=4.6
stiv31 [10]

The Average velocity for the bacterium is 0.75 unit/sec.

<u>Explanation:</u>

The given values are in the vector form

Where,

dS = distance covered

dT = time interval

Now, to calculate distance covered, we have

|d S|=\sqrt{d S^{2}}

&

d S=r_{2}-r_{1}

d S=(4.6 i+1.9 k)-(2.2 i+3.7 j - 1.2 k)

d S=(4.6-2.2) i+(0-3.7) j+(1.9+1.2) k

d S=2.4 i-3.7 j+3.1 k

Now, putting these values in the standard formula to evaluate the average velocity, we get;

v_{a v g}=\frac{|\mathrm{d} S|}{d T}

v(a v g)=\frac{|\sqrt{\left\{\left(2.4^{2}\right)+\left(3.7^{2}\right)+\left(3.1^{2}\right)\right\}}|}{7.2}

As dT=7.2 sec

Now,

Solving the equation, we get;

v(a v g)=\frac{5.390732789}{7.2}

\begin{aligned}&v(a v g)=\frac{5.39}{7.2}\\&v(a v g)=0.748611111\\&v(a v g)=0.75 \text { units / sec }\end{aligned}

Hence, the average velocity for the bacterium is 0.75 unit/sec.

3 0
3 years ago
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