# 2d Kinematics Problem Final Velocity

## Homework Statement

http://imgur.com/fGYf0

Stuck on #3

## Homework Equations

V = Vi + a*t
Y = (1/2)gt^2 + (ViY * t) + Yi

## The Attempt at a Solution

I have found the vertical and horizontal components and the initial velocity.
ViX = 6.2
ViY = 9.922
Vi = 11.7
Yf = 0
Yi = 7
Xi = 0
X = ?
Vf = ?
a (acceleration of gravity) = 9.8
(i = initial, f = final)

Answers to # 1 and # 2 are 9.922 and 5.0227 respectively.

Bump: Any help here?

cepheid
Staff Emeritus
Gold Member
Welcome to PF Succession!

Bump: Any help here?

Part 3 asks you to find the magnitude of the velocity at the end of travel, just before the object hits the ground. Well, what is the horizontal component of this velocity, at the end of the trip? Hint: do any forces act in the horizontal direction?

Okay, how about the vertical component of the velocity at the end of the trip? How would you find that? Hint: what height is it falling from? You know the "initial" velocity when it starts falling (i.e. at the point of max height), the acceleration, and the distance that it falls. Can you think of an equation that would allow you to solve for the final velocity (at the end of the fall) given those three things?

Welcome to PF Succession!

Part 3 asks you to find the magnitude of the velocity at the end of travel, just before the object hits the ground. Well, what is the horizontal component of this velocity, at the end of the trip? Hint: do any forces act in the horizontal direction?

Okay, how about the vertical component of the velocity at the end of the trip? How would you find that? Hint: what height is it falling from? You know the "initial" velocity when it starts falling (i.e. at the point of max height), the acceleration, and the distance that it falls. Can you think of an equation that would allow you to solve for the final velocity (at the end of the fall) given those three things?

Well the horizontal component of the initial velocity is 6.2, as given. I found the time (t) to be 2.578866342. Then I found Vy using Vy= gt + Viy, Vy = -15.35081607. Then I plugged my answer into a^2 + b^2 = c^2, Vy^2 + Vx^2 = V^2. -15.35081607^2 + 6.2^2 = V^2.
ended with -16.55558981. answer is still counted as incorrect, not sure where I went wrong, as one of my classmates used this same process and walked me through it and he got the answer right.

cepheid
Staff Emeritus