a fan is rotating at 90 rpm.It is then switched off. It stops after 21 revolutions. calculate the time taken by the frictional t
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The rock would be at a point 12 m from water at a time <u>4.8 s</u>.
Take the origin of the coordinate system at the top of the cliff. It is thrown upwards with a velocity u. When the rock is at a point 12 m from water, calculate the vertical displacement of the rock from the origin.
Use the equation of motion,
The rock falls under the acceleration due to gravity, directed down wards.
Substitute 18 m/s for u, -26 m for y and -9.8 m/s² for a=g.
Solve the quadratic equation for t.
Taking only the positive value,
After a time of <u>4.8 s</u> the rock would be at a distance of 12 m from water.