Speed and Velocity

Speed: does not depend on direction
Velocity: the speed and direction.

Calculating

Write this:
\text{speed} = \frac{distance}{time}
Instead of this:
\bar{v} = \frac{s}{t}
\text{gradient} = \text{velocity} in S-T graph
Instantaneous speed: gradient of S-T graph at one point
In a V-T graph: a =\text{gradient}=\frac{v-u}{t}, \text{Area under graph} = \text{distance}

Acceleration

Definition: the rate at which an object increases speed or velocity

![[Pasted image 20240903104236.png]]
1: True
2. velocity, acceleration
3. they must be touching each other
4. C

![[Pasted image 20240905090914.png]]
1. it means that the object keeps stationary.
2. False
3. it moves at a constant speed from 0 sec. to 5 sec. ,deceleration from 5sec. to 10sec. stays after 10 sec., and start to move again in the 15th sec.
4. \text{speed} = \frac{\text{distance}}{\text{time}} = \frac{10\ m}{5\ s} = 2 \ m\cdot s^{-1}
5. the gradient is speed.

![[Pasted image 20241008102724.png]]
1. the velocity doesn’t change, a=0
2. a curve with decreasing gradient(negative).
3. first increase with same gradient, then keeps steady
4. a=\frac{\Delta v}{\Delta t} = \frac{40\ m-20\ m}{15\ s-10\ s}=4\ m\cdot s^{-2}
5. {TotalDistance} = {Area}