FOUR USES OF CONCAVE MIRROR:Satellite dishes,headlights of a car, telescopes used for astronomical studies, and shaving mirrors because of there curved and reflective surface.
FIVE USES OF LENSES: Camera lens ,microscopes ,magnifying glass,eyeglasses,projector
Answer:
The heat causes the molecules on rubbing surfaces to move faster and have more energy.
Answer: This is called the Doppler effect, where waves shift frequency and wavelength as the source travels towards you (higher frequency, shorter wavelength) or away from you (lower frequency, longer wavelength)
Explanation:
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<span>D. Atoms of all elements contain protons, but the number of protons is different for every element.
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The spring starts out 22 cm long with nothing hanging on it.
Hanging 35 newtons of weight on it stretches the spring 1 meter.
Ellen is going to hang 250 grams of mass on the spring.
What's the weight of 250 grams of mass ?
Weight = (mass) x (acceleration of gravity in the place where the mass is) .
On Earth, the acceleration of gravity is 9.8 m/s² .
250 grams is 0.25 of a kilogram.
Weight of 250 grams = (0.25 kilogram) x (9.8 m/s²)
= (0.25 x 9.8) kg-m/s²
= 2.45 newtons .
2.45 newtons of weight is (2.45 / 35) of 35 newtons,
so it'll stretch the spring (2.45 / 35) of a meter.
2.45/35 = 0.07 of a meter = 7 centimeters.
The spring was 22 cm long with nothing hanging on it,
and the 250-gm weight stretched it 7 cm.
So with the weight hanging on it, it's (22 + 7) = 29 cm long.
