Solving Car Problem: Acceleration, Coasting and Deceleration

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A car weighing 1000 kg requires a force of 3000 N to accelerate at 3 m/sec². After accelerating for 45 seconds, it reaches a speed of 135 m/sec. During a 20-minute coast, the car maintains this speed, covering a distance of 162,000 meters, while no work is done since no net force acts on it. When decelerating to a stop, the kinetic energy is converted to other forms, and the force required to stop the car can be calculated using the mass and deceleration. The discussion highlights confusion around concepts of coasting, work, and energy dissipation.
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This problem is in various questions, so please bear with me.

Homework Statement


a) A car weighing 1000 kg is accelerated at 3 m/sec^2. What is the force required to produce that acceleration?.

b) in problem a- the car is accelerated for 45 seconds. How fast in m/sec is it going at the end of 45 sec?

c) in problem b- after the initial 45 second acceleration period, the car coasts (no net forces) for 20 minutes. ca) How fast is it going at the end of 20 minutes? How far did it go in hat 20 mintues?
cb) How much work was done on the car in that 20 minutes?
cc)At the end of the 20 minute coast period, the car is decelerated to a stop. How much work was done to bring the car to a stop?
cd)If the car took 35 seconds to stop, what was the force on the car and how far did it travel in the meters before it stopped

Homework Equations


a) F=ma
b) Vf(final velocity)= Vo(initial velocity) + a(acceleration)T(time)
c) F=ma or Vf=Vo+aT or S(distance)=VoT+ 1/2(a)(T^2) or W(work)=(F)D
(D is distance)

The Attempt at a Solution


a) F=ma
F=1000kg(3 m/sec^2)
F=3000 N

b) Vf=Vo+aT
Vf=0+3 m/sec^2(45 sec)
Vf=135 m/sec

c)PLEASE HELP!
 
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ca) coasting means what about its speed? If you know how fast it was going for the 20 minutes...how far did it cover?

cb) What is the definition of work? Can you do work if F=0?

cc) What can you say about the kinetic energy of the car as it goes from 135m/s to 0m/s? Where did that energy go?

cd) Re-use the technique you used in 3a.
 
berkeman said:
ca) coasting means what about its speed? If you know how fast it was going for the 20 minutes...how far did it cover?

cb) What is the definition of work? Can you do work if F=0?

cc) What can you say about the kinetic energy of the car as it goes from 135m/s to 0m/s? Where did that energy go?

cd) Re-use the technique you used in 3a.

ca) coasting means that the speed stayed the same throughout the 20 minutes?

cb) Work is the exertion or effort directed to produce or accomplish something. I guess that one can not do work if there is no force. I still don't postulate how this answers the question.

cc) The kinetic energy stops being present? The energy just dissipated.

cd) Reusing the formula F=ma would mean that I would have to multiply 1000kg by the acceleration of the car which I really do not know what it is.

I am very perplexed!@!#!
 
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