A train travels 75 kilometers in 5 hours and then 88 kilometers in 2 hours ? what is average speed
2 answers:
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B) 48.0 m/s
We can actually start to solve the problem from B for simplicity.
The motion of the rock is a uniformly accelerated motion (free fall), so we can find the final speed using the following suvat equation
where
is the final velocity
is the initial velocity (positive since we take downward as positive direction)
is the acceleration of gravity
s = 110 m is the vertical displacement
Solving for v, we find the final velocity (and so, the speed of the rock at impact):
A) 3.67 s
Now we can find the time of flight of the rock by using the following suvat equation
where
is the final velocity at the moment of impact
is the initial velocity
is the acceleration of gravity
t is the time it takes for the rock to reach the ground
And solving for t, we find