If an object moves with constant acceleration, its velocity must be constant als
ID: 1442155 • Letter: I
Question
If an object moves with constant acceleration, its velocity must be constant also. Always decrease. Change by the same amount each second. Change by varying amount depending on its spedd. A men leans over the edge of a cliff and throws a rock upward at 4.9 m/s. Neglecting air resistance, two seconds later the rock's speed is 9.8 m/s. 14.7 m/s. 4.98 m/s. zero none of the above Twelve seconds after starting from rest, an objects falling freely will have a speed of 10 m/S 50 m/s. more than 100 m/s. 100 m/s. A ball is thrown 125 meters upward and then falls the same distance back to Earth. Neglecting air resistance, its total time in the air is about 10 seconds. about 15 seconds. about 5 seconds. more than 20 seconds. A car accelerates at 2 meters per second per second. Assuming the car starts from Test, how much time does it need to accelerate to a speed of 30 m/s? 15 seconds 60 seconds 2 seconds 30 seconds none of these When a rock thrown straight upwards gets to the exact top of its path, its velocity is zero and its acceleration is about 10 meters per second per second. velocity is about 10 m/s and its acceleration is about 10 meters per second per second. velocity is zero and its acceleration is zero. velocity is about 10 m/s and its acceleration is zero. none of these An object covers a distance of 8 meters in the first second of travel another 8 meters during the next second, and 8 meters again during the third second. Its acceleration in meters per second per second is approximately 8. 24 5. 0.Explanation / Answer
9)
Avergae speed, = Distance / time
So Answer is Option (E)
10)
Acceleration = Velocity/time
Velocity = Acceleration * time
So we can clearly see, Velocity will change by the same amount each second.
Correct option - (C)
11)
Vi = 4.9 m/s
a = 9.8 m/s^2 downwards
Vf = Vi - a*t
Vf = 4.9 - 9.8*2
Vf = -14.7 m/s
-ve sign means downwards direction.
Correct option - (B)
(12)
V = u + a*t
V = 0 + 9.8*12
V = 117.6 m/s
Correct option - (C)
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