Question

If an object is thrown in an upward direction from the top of a building 160 ft high at an initial speed of 30 mi/h, what is
its final speed when it hits the ground? (Disregard wind resistance. Do not reflect negative direction in your answer.)
ft/s
110 fus
100 ft/s
097 ft/s
91 ft/s
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Answer 1

Answer:

We can use  2 g H = v2^2 - v1^2    or

v2^2 = 2 g H + v1^2

Since 88 ft/sec = 60mph   we have 30 mph = 44 ft/sec

The object will return with the same speed that it had initially so the object

starts out with a downward speed of 44 ft/sec

Then v2^2 = 2 * 32 ft/sec^2 * 160 ft + 44 (ft/sec)^2

v2^2 = (2 * 32 * 160 + 44^2) ft^2 / sec^2 = 12180 ft^2/sec^2

v2 = 110 ft/sec