Initial Velocity Question

by bwilhelm
Tags: initial, velocity
bwilhelm is offline
Aug31-07, 12:48 AM
P: 9
Am I anywhere near correct?

1. The problem statement, all variables and given/known data
A ball is thrown and upward and reaches it's maximum height in 1.80 sec.

A. Find Initial Velocity
B. Find Max Height Reaced
C. Find Velocity 1.15 sec after being thrown.

2. Relevant equations

3. The attempt at a solution
A. .5(-9.8)*1.8^2= -15.87 m/sec
B. -15.87+.5(-9.8)*1.8^2 = 31.74m
C. .5(-9.8)1.15^2= -6.48 m/sec
Phys.Org News Partner Science news on
SensaBubble: It's a bubble, but not as we know it (w/ video)
The hemihelix: Scientists discover a new shape using rubber bands (w/ video)
Microbes provide insights into evolution of human language
learningphysics is offline
Aug31-07, 01:36 AM
HW Helper
P: 4,125
No, not near correct. For part a, you used a displacement formula... so the result won't be a velocity...

Hint: for part a) use the fact that v2 = v1 + at. You know v2, a and t... use those to calculate v1.

For part b) you made a mistake with the formula... it should be s = v1*t + 1/2 at^2... you didn't multiply v1 by t... and also the v1 is wrong since part a was wrong...

For part c)... here again you use a displacement formula... so the result that comes out will be displacement not a velocity... 1/2 at^2 is a distance not a velocity.

Register to reply

Related Discussions
Initial Velocity question Introductory Physics Homework 3
Initial velocity, acceleration due to gravity question Introductory Physics Homework 9
Initial Velocity Question Introductory Physics Homework 62
Given an initial position and velocity of a receiver, find the velocity of a ball Introductory Physics Homework 7
Initial velocity question Introductory Physics Homework 1