A car starts from rest and attains a velocity of 40 metres per second in 20 seconds. it maintains this velocity for 30 seconds and then comes to rest in 25 seconds.
1. sketch the velocity time graph for the motion.
2. Calculate the acceleration of the body.
3. Calculate the total distance covered by the body
3 answers
acceleration= changevelocity/time
first 20 s
slope of v = a = 2 m/s^2
v = 0 + 2 t
x = (1/2)(2) t^2
at t = 20
v = 40 m/s
x = 400 m
from t = 20 to t = 50
v = 40 m/s
a = 0
at t = 50
v = 40
new a = -40/25
x = 400 + 40(30) = 1600
from t = 50 to t = 75
v = 40 - 40/25(t-50)
a = -40/25
x = 1600 +40(t-50) - 20/25(t-50)^2
x = 1600 + 20*25 = 2100 at end
slope of v = a = 2 m/s^2
v = 0 + 2 t
x = (1/2)(2) t^2
at t = 20
v = 40 m/s
x = 400 m
from t = 20 to t = 50
v = 40 m/s
a = 0
at t = 50
v = 40
new a = -40/25
x = 400 + 40(30) = 1600
from t = 50 to t = 75
v = 40 - 40/25(t-50)
a = -40/25
x = 1600 +40(t-50) - 20/25(t-50)^2
x = 1600 + 20*25 = 2100 at end
AE=40
EO=20=2ms-2
EO=20=2ms-2
3 answers