Calculate the kinetic energy in joules of an automobile weighing 2135 lb and traveling at 55 mph. (1 mile = 1.6093 km, 1 lb = 45
1 answer:
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Answer:
26.2 m/s
Explanation:
We can find the speed of the cannonball just by analyzing its vertical motion. In fact, the initial vertical velocity is
(1)
where u is the initial speed and is the angle of projection.
We can therefore use the following suvat equation for the vertical motion of the ball:
where is the vertical velocity at time t, and
is the acceleration of gravity. The time of flight is 3.78 s, so we know that the ball reaches its maximum height at half this time:
And at the maximum height, the vertical velocity is zero:
Substituting these values, we find the initial vertical velocity:
And using eq.(1) we now find the initial speed: