Amotion sensor acts as a transmitter when it sends out pulses and as a receiver when it listens for echoes. the delay ∆t between sending the pulse and receiving the echo is equal to 8.9 ms. the air temperature is equal to 20º c. part a what is the distance between the motion sensor and the object?

1.526 m

Explanation:

The motion sensor sends sound waves in air which travels at a speed of 343 m per second at 20 degree. If d be the distance of the reflecting object

total distance travelled = 2d

Time taken t = 8.9 x 10⁻³ s

velocity v  = 2d / t

343 = 2 d / (8.9 x 10⁻³)

d = 1.526 m

answer would be letter choice (a),   a ball resting on a shelf. would be another example of potential energy   >   stored energy > not moving.

a ball spinning on a finger   >   kinetic energy > moving energy

a ball rolling on the ground   >   kinetic energy   > moving energy

a   ball flying through the air   > kinetic energy   >   moving energy

hope that                                         : )

as we know our atmosphere or air have different levels. every level has other gasses, and every gas has another permeability. when the light comes from lower permeability to higher permeability, it changes its direction. so that means that when the light comes from the moon to the earth, it changes it's direction many more times. it basically means that the shape of the light part of the moon is changed on the earth.

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