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Scilla [17]
3 years ago
3

A ball weighing 10 kg traveling at 1.4 m/s hits and rebounds back off a wall and now travels 1.4 m/s in the opposite direction.

What is the work done on it?
Physics
1 answer:
Marizza181 [45]3 years ago
4 0

<em>NO work is done on the ball.</em>

Its momentum changes, but its kinetic energy doesn't.

<u>Before it hits the wall:</u>

Momentum = m v = (10 kg) x (1.4 m/s) = +14 kg-m/s

Kinetic energy = (1/2)(m)(v²) = (1/2)(10kg)(1.4)² = 9.8 Joules

<u>After it hits the wall:</u>

Momentum = m v = (10 kg) x (-1.4 m/s) = -14 kg-m/s

Kinetic energy = (1/2)(m)(v²) = (1/2)(10kg)(-1.4)² = 9.8 Joules

No change in energy  ==>  no work done on the ball.

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How far away is mars?
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Answer:

about: 110.14 million mi

Explanation:

the distance to Mars from Earth is 140 million miles (225 million kilometers).But, distance to Mars from Earth is constantly changing.

Hope that was helpful.Thank you!!!

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3 years ago
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Assume that two of the electrons at the negative terminal have attached themselves to a nearby neutral atom. There is now a nega
devlian [24]

Answer: its negative

Explanation: becase it is

5 0
3 years ago
1. An express train, traveling at 36 m/s, is accidentally sidetracked onto a local train track. The express engineer spots a loc
Colt1911 [192]

Answer:

(i) 12 seconds

(ii) 216 meters from the initial position

(iii) 132 meters from the initial position

(iv) No

Explanation:

Speed of express train =36 m/s

Speed of local train =11 m/s

The initial distance between the local train and passenger train =100 m.

Due to the application of breaks, the express train slows at the rare of 3.0 m/s^2.

So, the acceleration of the express train, a=-3 m/s^2.

(i) Let t be the time the express train takes to stop.

From the equation of motion,

v=u+at

where, v: final velocity, u: initial velocity, a: constant acceleration, t: time taken to change the speed from u to v.

In this case, v=0, u=36 m/s, a=-3 m/s^2

So, 0=36+(-3)t

\Rightarrow t= 36/3=12 seconds.

(ii) To compute the distance traveled, s, till the express train stops, using

v^2=u^2+2as

\Rightarrow 0^2=36^2+2(-3)s

\Rightarrow s=\frac{36\times36}{6}

\Rightarrow s=216 meters.

(iii) The local train is moving at a speed of 11 m/s

So, in 12 seconds, the distance, d, traveled by the local train

d= 11x12=132 meters [as distance= speed x time]

(iv) Let 0 be the reference position which is the initial position of the express train.

So, at the initial time, the position of the local train is at 100m.

After 12 seconds:

The position of the express train is at 216 m [using part (ii)]

and the position of the local train is at 100+132=232m  [using part (iii)].

So, the local train is still ahead of the express train, hence the trains didn't collide.

6 0
2 years ago
A car is designed to get its energy from a rotating flywheel with a radius of 1.50 m and a mass of 430 kg. Before a trip, the fl
fiasKO [112]

Answer:

a

  KE  =  7.17 *10^{7} \ J

b

 t = 6411.09 \ s

Explanation:

From the question we are told that

    The radius of the flywheel is  r =  1.50 \ m

      The mass of the flywheel is m  = 430 \ kg

          The rotational speed of the flywheel is w  =  5,200 \ rev/min = 5200 *  \frac{2 \pi }{60} =544.61 \ rad/sec

      The power supplied by the motor is  P  =  15.0 hp =  15 * 746 =  11190 \ W

         

     Generally the moment of inertia of the flywheel is  mathematically represented as

       I  = \frac{1}{2} mr^2

substituting values

       I  = \frac{1}{2}  ( 430)(1.50)^2

       I  = 483.75 \  kgm^2

The kinetic energy that is been stored is  

       KE  =  \frac{1}{2} * I * w^2

substituting values

        KE  =  \frac{1}{2} * 483.75 * (544.61)^2

        KE  =  7.17 *10^{7} \ J

Generally power is mathematically represented as

          P =  \frac{KE}{t}

=>      t =  \frac{KE}{P}

substituting the value

        t = \frac{7.17 *10^{7}}{11190}

        t = 6411.09 \ s

3 0
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Alex777 [14]

The answer of this question is called uplift i.e the rising of rock layers in geology is called uplift.

Uplift is the process in which there will be vertical elevation of earth surface due to various natural processes occurring inside the surface of earth like earth quakes. Sometimes uplift is also caused by the mountain building which hampers the balance of a particular region.

In the process of uplift,the rocks normally metamorphic rocks present underground will be brought up to the earth surface.The enhanced elevation will cause erosion of lot of materials on the surface of earth.


6 0
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