What time is required to reduce velocity from 157km/hr to 75km/hr?
How long does it travel during that time?
I got 108.2 seconds, and 3.21KM...
Yet on a similar question of..
Car travels at 65km/hr, brakes decelerate at 6m/s^2. To stop, it'll take 3.009s and 27.16M til it stops moving.. I'd like verification on this and help with the one above:D
2006-10-02 11:38:38 · 4 answers · asked by pugfug90 2 in Science & Mathematics ➔ Physics
The problem I'm having trouble with, I now have 3.25s and 104.72M. Contradicting all these posts:(
2006-10-02 11:46:52 · update #1
Daniel, isn't displacement=Final Velocity[75] - Initial Velocity[157]?
2006-10-02 11:48:40 · update #2
157km/h = 43.6m/s
75km/h = 20.8m/s
Difference = 22.8m/s
22.8 / 7 = 3.25 seconds
Average speed (43.6+20.8)/2 = 33.2 m/s
Distance 33.2 x 3.25 = 104.65 m
65km/h = 18.06m/s
18.06 / 6 = 3.01 seconds
Average speed 9.06m/s x 3.01s = 27.26 meters
Maybe we rounded numbers differently...
2006-10-02 11:50:25 · answer #1 · answered by Warren914 6 · 0⤊ 0⤋
157 - 75 = 82 km/s change in speed
a = 7 m/s^2
a = change in V over t
7 = 82 / t
t = 82 / 7 = 11.7
s = 1/2 a t^2
s = (1 / 2) * 7 * (11.7^2) = 479.1
2006-10-02 18:43:24 · answer #2 · answered by DanE 7 · 0⤊ 1⤋
Convert the speeds into meters per second, you only need to slow down about 23 meters per second.
2006-10-02 18:53:37 · answer #3 · answered by Anonymous · 0⤊ 0⤋
Your first one is wrong. Its about 4.8secs.
2006-10-02 18:39:30 · answer #4 · answered by Anonymous · 0⤊ 0⤋