reaches a velocity of 71.0 m/s when it takes off. What must its acceler- 13. An
ID: 1878420 • Letter: R
Question
reaches a velocity of 71.0 m/s when it takes off. What must its acceler- 13. An airplane 14. An airplane accelerates at 3,00 m/s from a velocity of 21.0 m/s over a distance of 15. ation be if the runway is 1.00 km long? 535 m. What is its final velocity? A bullet is fired vertically upward and reaches a height of 2150 m. (a) Find its ini- tial velocity. (b) How long does it take to reach its maximum height? (c) How long is it in flight? A rock is thrown down with an initial speed of 10.0 m/s from a bridge to the water below. It takes 2.75 s for the rock to hit the water. (a) Find the speed of the rock as it hits the water. (b) How high is the bridge above the water? 16.Explanation / Answer
13) Use equation of kinematics
v2 - u2 = 2ad
1 km = 1000 m
712 - 0 = 2*a*1000
a = 2.5205 m/s2
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14. Again use the above equation
v2 - u2 = 2ad
v2 - 212 = 2*3*535
v = 60.42 m/s
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15. again use the same equation
v2 - u2 = 2ad
02 - u2 = 2*(-9.8)*2150
(a) Initial velocity (u) = 205.3 m/s
(b) Time taken to reach 2150 m
v = u + at
0 = 205.3 + (-9.8)t
t = 20.94 seconds
(c) Total time in air ( going up and then coming down) = 2*t = 41.89 sec
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As per chegg guidelines, we should solve only one question but I have solved 3 to make you understand the concept. Now, you can solve the last question easily.
Hint for question 16. Use v = u + at
here v = 0 , u = 10 m/s, a = 9.8 m/s2 ( a is not negative as rock is going towards the earth)
solve for t.
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