Physics

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?

1. 👍 0
2. 👎 0
3. 👁 178
1. 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^2-V0^2)/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.

1. 👍 0
2. 👎 0
posted by Henry

Similar Questions

1. 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

asked by Kelsey on September 10, 2013
2. 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

asked by seanso on January 22, 2012
3. 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

asked by Anonymous on January 28, 2014
4. 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

asked by Steph on October 6, 2008
5. 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

asked by Anushya on September 29, 2014
6. Physics

Car A is 12 m ahead of car B on a straight stretch of road. Car A starts from rest and accelerates away from B at 4.0 m/s2. Two seconds later B starts from rest and accelerates after A at 6.0 m/s2. How long will it take B to catch

asked by John on February 7, 2017
7. physics

Q2. A box rests on the (frictionless) bed of a truck. The truck driver starts the truck and accelerates forward. The box immediately starts to slide toward the rear of the truck. Discuss the motion of the box, in terms of

asked by beckii on November 14, 2007
8. physics

A truck with a mass of 2.00x10^3 kg is coasting along a straight level road at 250.0 m/s. It comes to rest in 300.0m. How much work is done by friction in bring the truck to a stop?

asked by Anonymous on May 20, 2016
9. Physics

A truck starts from rest and accelerates at 2.0 m/s² for 4.0 s. How far will it have gone at the end of this time?

asked by Anonymous on January 29, 2016
10. Physics

a truck travelling along at straight road sounds its horn, which has a frequency of 500HZ. if an observer besides the road behind the truck measures the frequency to be 480Hz ,how fast is the truck moving?assume the speed of sound

asked by daniel zhao on November 28, 2018

More Similar Questions