Question

how do you find the speed and velocity on a volocity time graph

Answer 1

The speed is just the 'magnitude' number on the y axis (vertical axis).

Answer 2

the question is find the times at which the velocity and speed is increasing and i dont understand

Answer 3

its question b

Answer 4

First, velocity is a vector, ok,
If you read the graph from 0 to 2 seconds, the velocity has \(\color{blue}{increased}\) from zero to -15m/s , the negative means that the object is moving \(\color{green}{opposite}\) from the chosen positive direction.

From 2 to 9s, the velocity isn't increasing or decreasing.
From 9 to 11s, the velocity is \(\color{red}{decreasing}\) from -15m/s to 0, and the object has no velocity means it's not moving.

Answer 5

oh ok but how about the speed

Answer 6

Same thing applies, speed increasing at 0 to 2 seconds, and decreasing at 9 to 11s.
I've used velocity just to tell you that negative doesn't mean the speed is decreasing.

Answer 7

how can you differentiate both of them

Answer 8

Speed has just magnitude, velocity is magnitude and direction, you can differentiate it like
if let's say the object moves from 0 to -100m/s. then speed will be 0 to +100m/s. It's the direction/sign that matters