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3 years ago

Which of the following is a unit of speed?

Physics

2 answers:

exis [7]3 years ago

8 0

Answer:

D, km/s^2

Explanation:

This is a unit of speed because it is saying kilometers over seconds squared, and that is a unit of speed similar to miles per hour or mph or m/h.

dangina [55]3 years ago

7 0

Answer:

Option c that it means cm/year.

Explanation:

Nm means nanometer, 1x10^9m

Km/s^2 is acceleration

h.. it may be height

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A piece of amber is charged by rubbing with a piece of fur. If the net excess charge on the fur is +8.0 nC (+8.0 10-9 C), how ma

Ann [662]

Answer:

Number of electron on the fur will be $5\times 10^{10}electron$

Explanation:

We have given net charge on the fur $q=8nC=8\times 10^{-9}C$

Charge on one electron $e=1.6\times 10^{-19}C$

Let there are n number of electrons

So $ne=8\times 10^{-9}$

$n\times 1.6\times 10^{-19}=8\times 10^{-9}$

$n=5\times 10^{10}electron$

So number of electron on the fur will be $5\times 10^{10}electron$

6 0

3 years ago

If a sound wave travels through air at a speed of 345 m/s, what would be the frequency of a 0.80 m long wave?

den301095 [7]

Answer:

Explanation:431.3

7 0

3 years ago

1. How do energy and matter recycle in a closed-loop system?

Makovka662 [10]

Answer:

In a closed-loop system, matter is used to generate energy, and the energy generated is used to produce matter, and the cycle goes on without end.

Explanation:

A closed-loop system is one in which materials or energy is recycled without end through a production cycle. This means that a raw material is used to produce a finished product, and the finished product at the end of its use cycle is converted back and used as a raw material to produce more of it again. Energy and matter can also be cycled in the same way in an energy and matter closed-loop system, converting matter to energy, and the energy is put back into the production of more of the matter.

7 0

3 years ago

A high-jumper, having just cleared the bar, lands on an air mattress and comes to rest. Had she landed directly on the hard grou

Hoochie [10]

Answer:

e. the air mattress exerts the same impulse, but a smaller net avg force, on the high-jumper than hard-ground.

Explanation:

This is according to the Newton's second law and energy conservation that the force exerted by the hard-ground is more than the force exerted by the mattress.

The hard ground stops the moving mass by its sudden reaction in the opposite direction of impact force whereas the mattress takes a longer time to stop the motion of same mass in a longer time leading to lesser average reaction force.

Mathematical expression for the Newton's second law of motion is given as:

$F=\frac{dp}{dt}$ ............................................(1)