Solution:
We have,
Power [P] = 25000 Watt
Mass [m] = 6000 kg
Height [h] = 20 metres
Time [t] = ?
Now,
P = W/t = F x d/t = mxgx h/t
Or, 25000 = 6000 x 10 x 20/25000 [.......g = 10
m/s^2]
Or, t = 6000 x 10 x 20/25000
Or, t = 1200/25
Therefore, t = 48 second
Hence, the required time for the crane to lift the load is 48 seconds.
half-life? what do you mean
Answer:
Approximately
, assuming that the gravitational field strength is
.
Explanation:
Let
denote the required angular velocity of this Ferris wheel. Let
denote the mass of a particular passenger on this Ferris wheel.
At the topmost point of the Ferris wheel, there would be at most two forces acting on this passenger:
- Weight of the passenger (downwards),
, and possibly - Normal force
that the Ferris wheel exerts on this passenger (upwards.)
This passenger would feel "weightless" if the normal force on them is
- that is,
.
The net force on this passenger is
. Hence, when
, the net force on this passenger would be equal to
.
Passengers on this Ferris wheel are in a centripetal motion of angular velocity
around a circle of radius
. Thus, the centripetal acceleration of these passengers would be
. The net force on a passenger of mass
would be
.
Notice that
. Solve this equation for
, the angular speed of this Ferris wheel. Since
and
:
.
.
The question is asking for the angular velocity of this Ferris wheel in the unit
, where
. Apply unit conversion:
.
The forces in some car crashes are greater than others; therefore, the body can be more severely injured by greater and more powerful forces. I hope this helped! :^)