Question

We Crawled along through the city traffic at 6m/s for five minutes,then we left the city ,&we gradually accelerated to 24m/s in 20s. we kept going at this speed for 2minutes ,but then i noticed an accident on the road ahead and i braked , so that we came to ahalt in 8s. then find the car's acceleration & deceleration ??? & draw the graph to represent this journey???

Answer 1

first 300 seconds (five min)
acceleration = 0
velocity = 6 m/s
x = 0 + 6 t linear
v = 6
at 300 seconds x = 6*300 = 1,800

second 20 seconds, t = 300 to t = 320
initial x = 1,800
initial speed = 6
final speed = 24
acceleration = (24-6)/20 = 18/20 = 0.9 m/s^2
final x = 1800 + (24+6)/2 * 20 = 1800 + 300 = 2,100

third segment
initial x = 2,100 m
speed = 24 m/s constant no acceleration
for 120 seconds so final time = 320+120 = 440 s
final x = 2,100 + 120*24 = 2100+2880 = 4980

fourth segment
initial x = 4980
initial v = 24
final v = 0
average v = 12 m/s
x = 4980 + 12 * 8 = 4980 + 96 = 5076
acceleration = -24/8 = -3 m/s^2

Answer 2

draw the graph

Answer 3

draw graph

Answer 4

Wesd