Dr Pusey

www.puseyscience.com

Velocity is the change of position with time

𝑣 =𝑠

𝑡

Acceleration is the change of VELOCITY with time

𝑎 =∆𝑣

𝑡=

(𝑣−𝑢)

𝑡

Here:v = final velocity (at the end)

u= initial velocity (at the start)t = time taken

If Road Runner starts running and reaches a speed of 400m/s in 10 seconds, what was his acceleration?

𝑎 =(400−0)

10=

(400)

10= 40𝑚/𝑠2

This dragster reaches a top speed of 150m/s in 3.7 seconds. What was it’s acceleration?

This dragster reaches a top speed of 150m/s in 3.7 seconds. What was it’s acceleration?

𝑎 =(150−0)

3.7=

(150)

3.7= 40.5𝑚/𝑠2

Since the dragster is travelling at 150m/s, what will the speedo show in km/h? Convert this number to km/h.

Since the dragster is travelling at 150m/s, what will the speedo show in km/h? Convert this number to km/h.

Convert the mtres to kilometres (it must go down, so divide)

150/1000 = 0.15km/s

Now convert the hours to seconds (it must go up, so multiply)

0.15 * 60 * 60 = 540km/h

The driver pops his parachute at 150m/s. It slows him down to 40m/s in 1.25 seconds. What was his acceleration?

The driver pops his parachute at 150m/s. It slows him down to 40m/s in 1.25 seconds. What was his acceleration?

𝑎 =(40−150)

1.25=

(−110)

1.25= −88𝑚/𝑠2

The car was DECELERATING AT 88m/s2