Why images formed by a plane mirror are always erect?
Answers
Answer:
because it's a concave mirror
Answer:
A body covers 20m in 2 sec and 80 m in 4 seconds from the start along a straight line. If it is moving with constant acceleration, how much distance will it cover in the next 4 seconds?
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3 Answers
Satya Parkash Sud, M.Sc. Physics & Nuclear Physics, University of Delhi (1962)
Answered Sep 27, 2017 · Author has 3.1k answers and 7.9m answer views
Let the initial velocity of the body be u m/s; and the constsnt acceleration be a m/s². Then displacemet (distance covered) of the body after t second is given by
s = u t + ½ a t² ———————————-(1)
The body covers 20 m in 2s and 80 m in 4 s.
20 = u×2 + ½ a 2²; => 20 = 2 u + 2 a
u + a = 10 —————————————(2)
80 = u×4 + ½ a 4²; => 80 = 4 u + 8 a; this gives,
u + 2 a = 20 ——————————————(3)
Solving (2) and (3) for u and a we get
u = 0 m/s and a = 10 m/s² ————————(4)
To obtain the distance covered in the next 4s we need to find the velocity at the beginning of this interval using,
v = u + a t => v = 0 m/s + 1...
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