- #1

S313

- 6

- 2

## Homework Statement

The initial speed of a ball up an inclined plane is 3 m/s upwards. The ball reaches its highest point after 1.2 seconds. a) find the acceleration. b) how far has the ball gotten during this time? c) how far has the ball rolled after 0.4 s and after 2.4 seconds?

## Homework Equations

The problem is from the first chapter of my physics book, which has only introduced the 4 linear motion formulas (with constant acceleration): v = v0 + at, s = v0t + 1/2at^2, s = ((v0 + v)/2)t and v^2 - v0^2 = 2as.

So here, v0 = 3 m/s and t = 1.2 s

3. The Attempt at a Solution

3. The Attempt at a Solution

For part a) I got: a= v/t = 3/1.2 = 2,5 m/s^2

For part b) I used the s = v0t + 1/2at^2 = (3)(1.2) + (1/2)(2.5)(1.2)^2 = 3.6 + 1.8 = 5.4 m

For part c) I couldn't work out the answer.

The final answer is 1.8 m according to the book (I get 5.4), which means that v0 should be 0 (in this way s = (1/2)at^2 will only be used as v0t = 0. But why is v0 = 0? the velocity at the highest point is 0, but initial velocity is supposed to be 3 m/s upwards? why is this ommitted?