a stone dropped from the roof at a velocity of 6m/s2 and reaches the ground with the velocity of 18m/s.how high is the roof from the ground
14.69 meters
To find the height of the roof from the ground, we can use the kinematic equation:
v^2 = u^2 + 2as
Where:
v = final velocity of the stone (18 m/s)
u = initial velocity of the stone (0 m/s, as it was dropped from rest)
a = acceleration due to gravity (which is approximately -9.8 m/s^2, considering downward direction as negative)
s = displacement (unknown)
Plugging in the values, we get:
(18)^2 = (0)^2 + 2 * (-9.8) * s
Simplifying the equation:
324 = -19.6s
Dividing both sides by -19.6:
s ≈ -16.53
The displacement, s, is negative because the stone is falling downwards. However, for calculating the height, we need to take the absolute value of s.
Height = |s| = |-16.53| = 16.53 meters
Therefore, the height of the roof from the ground is approximately 16.53 meters.
6 m/s^2 is not a velocity. It is an acceleration.
See the first "related question" below, which makes the same mistake.