circular motion problem help?

Question

1) a 615 kg racing car completes one lap in 14.3 s around a circular track with a radius of 50.0m. the car moves at constant speed.
a) what is the acceleration of the car?



2)an athlete whirls in a 7.00 kg hammer tied to the end of 1.3m chain in a horizontal circle. the hammer makes one revolution in 1.0s.
1))what is the centripetal acceleration of the hammer?




3)the carnival ride has a 2.0m radius and rotates once of a rider.
a)find the speed of a rider.
b)find the centripetal accleration of a rider
c)what produces this accleration?
d)when the floor drops down, riders are held up by friction. draw motion and free body up by friction. draw motion and free body diagrams of the situation
e)what coefficient of static friction is needed to keep the riders from slipping?

i need help with these question.....please.........

Answer 1

1.The only acceleration the car has is centripetal

ac=V^2/R

2. Again
ac= V^2/R

3. What is "rotates once of a rider"?
a) ?
b)ac=V^2/R
c) Think inertia. The mass want to continue on a straight line and force apposing the centripetal force keeps that mass inside the circular path.
d)Force of friction f equal to the weight W of the rider
f=u m ac
W=mg the coefficient of friction is
u= g/ac

Answer 2

1. The only acceleration in this problem is centripetal and is equal to v^2 / r where v is the velocity of the car and r the radius of the circular track.

2. Again, the centripetal acceleration is v^2 / r. The distance traveled in one second is the circumference of the circle, 2 pi r.

3. Incomplete; you probably meant to give us the rotational velocity. Anyway, (b) is v^2 / r; (c) is the contact force with the side wall, and (d) the riders are held up by the friction component of that contact force, uN. Note that N is a centripetal force in this problem.

Trivia: I once watched my seven year old daughter ride this thing seventeen times in a row, and only quit then because we were out of time.