Go Back   Physics Help Forum > College/University Physics Help > General Physics

General Physics General Physics Help Forum

Reply
 
LinkBack Thread Tools Display Modes
Old Sep 27th 2018, 11:18 PM   #1
Junior Member
 
Join Date: Sep 2018
Posts: 1
Homework Question

Just needed help on this, if anyone could get me the answer on it that would be awesome.

Pretend you are standing on top of a tall building and you decide to throw a water balloon down to the sidewalk. If you throw the water balloon with an initial velocity of 12 m/s and the building is 20 m high how long will it take to hit the ground?

Assume there is no air resistance.

Thanks!
crimraider13 is offline   Reply With Quote
Old Sep 28th 2018, 02:56 PM   #2
Physics Team
 
ChipB's Avatar
 
Join Date: Jun 2010
Location: Morristown, NJ USA
Posts: 2,321
You should memorize and use the basic equation of linear motion for bodies under constant acceleration:

y(t) = y_0 + v_0 t + (1/2)at^2

You may see this equation with different terms, such as using 'x' or 'd' for displacement, or v_i for initial velocity; whatever symbols you're used to you should use; it really doesn't matter which version you use as long as you are consistent.

Here you want to solve for time 't' given the initial displacement y_0 = 20m, the final displacement y=0, the initial velocity v_0 = -12 m/s, and acceleration a = g = -9.8m/s^2. By the way, you don't say what the direction is for he initial toss of the water balloon - it makes a big difference! If upward then v_0 = +12 m/s; if downward then v_0 = -12 m/s; if horizontal then v_0 = 0.

You can solve for 't' using the quadratic equation. Note that this will give you two answers - one with a positive value for 't' and one with a negative value. The positive value is the correct answer for this problem, but what do you think the negative value of 't' denotes?

Post back with your solution and we'll check it for you.

Last edited by ChipB; Sep 28th 2018 at 03:04 PM.
ChipB is offline   Reply With Quote
Reply

  Physics Help Forum > College/University Physics Help > General Physics

Tags
acceleration, falling, homework, question



Thread Tools
Display Modes


Similar Physics Forum Discussions
Thread Thread Starter Forum Replies Last Post
Homework question .......please help me fares General Physics 2 Jul 16th 2018 05:58 AM
Homework question help........!!!!!!!! fares General Physics 2 Jul 15th 2018 11:41 AM
Homework question help Edemardil General Physics 2 Jul 12th 2018 04:20 PM
College Homework Help, Statistics Homework Help, Finance Homework Help, Accounting Ho marklee Energy and Work 0 Jan 19th 2010 02:23 AM
Physics Homework Question?? KaylaN Kinematics and Dynamics 1 Sep 3rd 2009 12:43 AM


Facebook Twitter Google+ RSS Feed