## cutie.patootie 2 years ago A 5.5 kg bowling ball initially at rest is dropped from the top of a 12 m building. It hits the ground 1.75 s later. Find the net external force on the falling ball.

1. yrelhan4

s=1/2at^2 you have s and t find a. net force=ma. plug and solve.

2. cutie.patootie

What is s?

3. yrelhan4

s-->distance travelled a--> acceleration due to gravity here t-->time taken

4. cutie.patootie

Okay, thanks:)

5. yrelhan4

cheers!

6. cutie.patootie

I 431.2N but that isn't an option..

7. yrelhan4

8. cutie.patootie

So this is what I did.. s=12m a=? t=1.75s 12=((1.75)^2a)/2 12=(3.0625a)/2 24=3.0625a a=7.84 netforce=55*7.84 netforce=431.2N

9. yrelhan4

Net acceleration. a = 2*12/1.75² Net force ma = 5.5* 2*12/1.75² = 43.12 N

10. cutie.patootie

I get what your saying now. But the only problem is my choices are 120N, 54N, & 0N. But I can rule out 0N automatically

11. yrelhan4

hmm. no idea. sorry.

12. cutie.patootie

Its okay, thanks for your help though :) I really do appreciate it

13. yrelhan4

you're welcome. good luck. :)