Mechanics, Uniform Circular Motion

[priscilla89]

Homework Statement

A flat racetrack viewed from above has curves with radius of 50.0 meters and 100. meters. A car having a mass of 1.00 x 10^3 kilograms moves counterclockwise around the track at a constant speed of 20.0 meters per second. It takes the car 20.0 seconds to travel from C to D.

Radius = 50.0 meters and 100. meters
Mass = 1.00 x 10^3 kilograms
Speed = 20.0 m/s
Time = 20.0 s from C to D

1. What is the magnitude of the net force acting on the car while it is moving from A to B?
2. Calculate the net force acting on the car while it is moving from B to C.
3. Calculate the distance from C to D.
4. Compare the magnitude of the centripetal acceleration of the car while moving from D to A, to the magnitude of the centripetal acceleration of the car while moving from B to C.
5. Compare the magnitude of the car's momentum at D to the magnitude of the car's momentum at B.
6. Compare the magnitude of the centripetal acceleration of the car at A to the magnitude of the car's centripetal acceleration at A if additional passengers were riding in the car.

Homework Equations

2 = {Pie}r / t
ac = v^2 / r
Fc = ma{c}

The Attempt at a Solution

I'm sorry I just don't understand but I know the equations to use. Ok, but ill attempt to do it at least.
1. I don't know anything much about net force.
Would this be the equation? a = Fnet / m
I'm just really sorry but I only know about centripetal force, average speed and the centripetal acceleration. I don't know about the magnitude of the net force only magnitude of centripetal acceleration.

I would really appreciate it if you can help me. I do understand I should learn this but I wish I knew the equation to use for net force.

Okay I understand 91.
91. ac = v^2 / r
ac = (20)^2 / 50
ac = 8 for D to A

ac = (20)^2 / 100
ac = 4 for B to C

Is this correct? Thanks I really appreciate this.

 

[Delphi51]

Welcome to PF, Priscilla!
It is difficult to understand the question without seeing the diagram. Perhaps you could sketch it in a paint program, save the painting to a photo site like photobucket.com and post a link here.

Yes, Fnet or Ftotal is always equal to ma.
Likely the only force you have on those turns is Fc = mv²/r = ma so your calc is probably correct.

 

[priscilla89]

Homework Statement

A flat racetrack viewed from above has curves with radius of 50.0 meters and 100. meters. A car having a mass of 1.00 x 10^3 kilograms moves counterclockwise around the track at a constant speed of 20.0 meters per second. It takes the car 20.0 seconds to travel from C to D.

Radius = 50.0 meters and 100. meters
Mass = 1.00 x 10^3 kilograms
Speed = 20.0 m/s
Time = 20.0 s from C to D

1. What is the magnitude of the net force acting on the car while it is moving from A to B?
2. Calculate the net force acting on the car while it is moving from B to C.
3. Calculate the distance from C to D.
4. Compare the magnitude of the centripetal acceleration of the car while moving from D to A, to the magnitude of the centripetal acceleration of the car while moving from B to C.
5. Compare the magnitude of the car's momentum at D to the magnitude of the car's momentum at B.
6. Compare the magnitude of the centripetal acceleration of the car at A to the magnitude of the car's centripetal acceleration at A if additional passengers were riding in the car.

Homework Equations

2 = {Pie}r / t
ac = v^2 / r
Fc = ma{c}

The Attempt at a Solution

I'm sorry I just don't understand but I know the equations to use. Ok, but ill attempt to do it at least.
1. I don't know anything much about net force.
Would this be the equation? a = Fnet / m
I'm just really sorry but I only know about centripetal force, average speed and the centripetal acceleration. I don't know about the magnitude of the net force only magnitude of centripetal acceleration.

I would really appreciate it if you can help me. I do understand I should learn this but I wish I knew the equation to use for net force.

Okay I understand 91.
91. ac = v^2 / r
ac = (20)^2 / 50
ac = 8 for D to A

ac = (20)^2 / 100
ac = 4 for B to C

Is this correct? Thanks I really appreciate this.

Okay, here is a diagram for the problem. Thanks a lor!

 

[Delphi51]

Great, the diagram really helps. Your work so far looks very good.
I see some of the questions involve no calculations, like #1.