• Support PF! Buy your school textbooks, materials and every day products Here!

BASIC gravity problem

  • Thread starter TG3
  • Start date
  • #1
TG3
66
0
I feel like an idiot asking this, it's review of a previous course as we start a new quarter, and I KNOW I used to be able to do this.... but I don't remember how too. Time to review...

Homework Statement



A tomato is dropped from 100 feet above the ground. At what speed does it hit the ground?
How long does it take to fall the last 100 feet?

Homework Equations



Acceleration due to gravity is 32 ft/sec^2

The Attempt at a Solution



If I recall correctly, delta X = 1/2 at^2
100 = 1/2 32 T^2
200 = 32 T^2
6.25 = T^2
T = 2.5
Tomato hits ground after 2.5 seconds.
So now, plugging that in:
32 (2.5)^2 = 200... which is definitely not right.
 

Answers and Replies

  • #2
LowlyPion
Homework Helper
3,090
4
I feel like an idiot asking this, it's review of a previous course as we start a new quarter, and I KNOW I used to be able to do this.... but I don't remember how too. Time to review...

Homework Statement



A tomato is dropped from 100 feet above the ground. At what speed does it hit the ground?
How long does it take to fall the last 100 feet?

Homework Equations



Acceleration due to gravity is 32 ft/sec^2

The Attempt at a Solution



If I recall correctly, delta X = 1/2 at^2
100 = 1/2 32 T^2
200 = 32 T^2
6.25 = T^2
T = 2.5
Tomato hits ground after 2.5 seconds.
So now, plugging that in:
32 (2.5)^2 = 200... which is definitely not right.
Doing it your way, the last step would be V = a*t not t2

Otherwise you could take the Potential energy to kinetic energy relationship:

m*g*h = 1/2*m*V2

or

V2 = 2*g*h
 

Related Threads for: BASIC gravity problem

Top