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3 years ago

15

Which of the following is not a use of electromagnetic waves? a night-vision bremote controls c x-rays d all are used of electro

magnetic wavesbremote controls is not a use of electromagnetic waves?

1 answer:

sergey [27]3 years ago

4 0

Use of electromagnetic because it moves very faster than others for example xrays theynar very very slow so that not It it is d.

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Physical values in the real world have two components: magnitude and

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Beings on spherical asteroid have observed that a large rock is approaching their asteroid in a collision course. At 7514 km fro

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Answer:

c. $4.582\times10^{21} kg$

Explanation:

$r_{i}$ = Initial distance between asteroid and rock = 7514 km = 7514000 m

$r_{f}$ = Final distance between asteroid and rock = 2823 km = 2823000 m

$v_{i}$ = Initial speed of rock = 136 ms⁻¹

$v_{f}$ = Final speed of rock = 392 ms⁻¹

$m$ = mass of the rock

$M$ = mass of the asteroid

Using conservation of energy

Initial Kinetic energy of rock + Initial gravitational potential energy = Final Kinetic energy of rock + Final gravitational potential energy

$(0.5) m v_{i}^{2} - \frac{GMm}{r_{i}} = (0.5) m v_{f}^{2} - \frac{GMm}{r_{f}} \\(0.5) v_{i}^{2} - \frac{GM}{r_{i}} = (0.5) v_{f}^{2} - \frac{GM}{r_{f}} \\(0.5) (136)^{2} - \frac{(6.67\times10^{-11}) M}{(7514000)} = (0.5) (392)^{2} - \frac{(6.67\times10^{-11}) M}{(2823000)} \\M = 4.582\times10^{21} kg$

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A 1.50x103-kilogram car is traveling east at 30 meters per second.

frez [133]

Answer:

$39000\ \text{kg m/s}$

West

Explanation:

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t = Time = 9 seconds

u = Initial velocity = 30 m/s

v = Final velocity = 0

Impulse is given by

$J=m(v-u)\\\Rightarrow J=1.3\times 10^3(0-30)\\\Rightarrow J=-39000\ \text{kg m/s}$

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