3.12
Recall that when an object falls towards the ground and is only influenced by gravity, it is said to be in free-fall. Under the earth's gravity, an object falls with constant acceleration, known as acceleration due to gravity.
The kinematic equations for constant acceleration are used to solve the problems of freely falling bodies.
For example, a stone is freely dropped from the top of a cliff into a river. What will be its position and velocity after 5 seconds?
The known quantities are the initial position, the initial velocity, the acceleration due to gravity, and time.
Considering the vertical coordinate of the y-axis, the cliff top is the origin, and the upward direction is negative. The unknown quantities are the position and velocity of the stone after 5 seconds.
Substituting the known values in the kinematic equations gives 122.5 meters as the distance traveled and 49 meters per second as the velocity of the stone.
An object falling without any air resistance under the influence of gravitational force is said to be in free-fall. For free-falling bodies, the accel…
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