Physics
posted by Isaac .
A truck on a straight road starts from rest and accelerates at 2.8 m/s^2 until it reaches a speed of 16 m/s. Then the truck travels for 16s at constant speed until the brakes are applied,stopping the truck in a uniform manner in an additional 3.6 s.
How long is the truck in motion?
Answer in units of s
What is the average velocity of the truck for the motion described?
Answer in units of m/s
So I've done the first part already which is 25.31 s, but when i try to find the average velocity for part two. I keep getting it wrong...can anyone show me the process on how to correctly do the second one?

Physics 
Henry
V = Vo + a*t = 16 m/s.
0 + 2.8*t = 16
t1 = 5.71 s. to reach 16 m/s.
d1 = 0.5a*t^2 = 0.5*2.8*5.71^2 = 45.65 m
d2 = V*t2 = 16 * 16 = 256 m.
t1+t2+t3 = 5.71 + 16 + 3.6 = 25.31 s in
motion.
V = Vo + a*t = 0
16 + a*3.6 = 0
3.6a = 16
a = 4.44 m/s^2.
d3 = (V^2V0^2)/2a = (0(16^2)/8.88 =
28.8 m. To stop.
Vavg = (d1+d2+D3)/(t1+t2+t3) =
(45.65+256+28.8)/25.31 = 13.06 m/s.
Respond to this Question
Similar Questions

College Physics!!!
A truck on a straight road starts from rest accelerating at 2.0 m/s2 until it reaches a speed of 20 m/s. Then the truck travels for 20 s at constant speed until the brakes are applied, stopping the truck in a uniform manner in an additional … 
physics
A 4000 kg truck traveling at constant velocity and a braking force of 20000 N is suddenly applied. It takes 6 seconds for the truck to stop. a) what is the deceleration of the truck? 
Physics
A truck traveling at a constant speed of 40.0 km/h applies its brakes and comes to a complete stop in 5.0 s. The truck starts again and accelerates at a constant rate of 0.80 m/s2. After restarting, how far does the truck travel before … 
physic
A police car is travelling in a straight line with constant speed vp.A truck travelling in the same direction with speed 3/2 vp passes the police car.The truck driver realizes that she is speeding and immediately begins to slow down … 
physics
A truck on a straight road starts from rest and accelerates at 2.0 m/s2 until it reaches a speed of 20 m/s. Then the truck travels for 20 s at constant speed until the brakes are applied, stopping the truck in a uniform manner in an … 
Physics
A truck on a straight road starts from rest and accelerates at 3.0 m/s2 until it reaches a speed of 18.1 m/s. Then the truck travels for 24.5 s at constant speed until the brakes are applied, stopping the truck in a uniform manner … 
physics
A certain truck can slow at a maximum rate of 4.6 m/s2 in an emergency. When traveling in this truck at a constant speed of 19 m/s the driver spots a large hole in the road 48.2 m in from of his position. The truck continues moving … 
Physics
A truck on a straight road starts from rest, accelerating at 2.00 m/s2 until it reaches a speed of 32.0 m/s. Then the truck travels for 76.0 s at constant speed until the brakes are applied, stopping the truck in a uniform manner in … 
Physics Grade 12
Heather is sitting on her car at a spotlight. At the instant light turns green, she starts accelerating at 2.2 m/s/s. At the same moment a truck rumbles past her car going a constant speed of 12.2 m/s. Heather is infuriated at being … 
physics
A truck on a straight road starts from rest, accelerating at 2.00 m/s2 until it reaches a speed of 11.0 m/s. Then the truck travels for 65.0 s at constant speed until the brakes are applied, stopping the truck in a uniform manner in …