Question

In 1977, Kitty O'Neil drove a hydrogen peroxide-powered rocket dragster for a record time interval (3.22 s) and final speed (663 km/h) on a 402 m long Mojave Desert track.(a) Determine her average acceleration during the race.(b) Determine her acceleration while stopping (it took about 20 s to stop).

Answer 1

a) 0.05719 km/s^2

b) 0.00921 km/s^2

Step-by-step explanation:

average acceleration can be calcuated as follows

`a=(\Delta v)/(\Delta t) = (v_f-v_i)/(t_f-t_i)`

a)

- In the initial time (
`t_i=0`), just before of race start the rocket is at rest. So
`v_i=0`.

- After 3.22 s the rocket reach 663 km/h, So
`t_f=3.22 s` and the
`v_f=663 km/h`. We convert units from km/h to km/s to have the same time units (seconds) the velocity would be:

`663 (km)/(h)*(1 h)/(3600 s) = 0.18467 km/s`

(take into accoun that 1 h=3600 s)

and acceleration is:

`a= (0.184167 km/s-0 km/s)/(3.22s-0s)= 0.05719 km/s^2`

b)

acceleration while stopping is calculate with the same formula but now

-we define the initial time (
`t_i=0`) the instant just before begining the stopping. At this instant the velocity is 663 km/h which is the same as 0.18467 km/s.

-After 20 seconds the rocket stops. So tex]t_f=20 s[/tex] and
`v_f=0`

So, acceleration is:

`a= (0km/s-0.184167 km/s)/(20s-0s)= 0.00921 km/s^2`