freefall question (1 Viewer)

[astroman]

A cat jumps straight up 4m. How much time does it spend in the top 2m (ascending and descending)?

i've gotten initial velocity of, 8.85437744847. I don't know what to do next and get the answer.

help......

 

[1008]

When the cat is jumping up, there is a vertical displacement of 4m. Assuming the cat is on Earth and has unit mass, the cat experiences a downward pull from gravity of -9.8ms-2. Note that when the cat is 4m into the air, its velocity would be zero and then it would return back to the ground. The whole process of getting from u = 8.85437744847 to v = 0 takes: u/9.8 = 0.90346s. Now you also know that:
.
Let delta y = 2, and solve the quadratic for t. This is the time it takes for the cat to get to the bottom 2m when ascending. Now subtract this from the total time t = 0.90346 seconds to get your top 2m.

Repeat this process for when the cat is descending, but remember in that case u = 0 as cat is in mid air.

 

[astroman]

bump

 

[1008]

Also, forgot to add, to find time for when the cat is descending, just used the delta y equation I've provided above with delta y = -2 and u = 0.

Hope this helps