(adsbygoogle = window.adsbygoogle || []).push({}); [SOLVED] Rotational Kinematics

1. The problem statement, all variables and given/known data

A person is riding a bicycle, and its wheels have an angular velocity of +18.0 rad/s. Then, the brakes are applied and the bike is brought to a uniform stop. During braking, the angular displacement of each wheel is +13.5 revolutions.

(a) How much time does it take for the bike to come to rest?

(b) What is the angular acceleration of each wheel?

2. Relevant equations

(a) θ = (ω0+ ω)t

(b) ω = ω0+ αt

3. The attempt at a solution

(a) +13.5 rev = (18.0 rad/s - 0 rad/s)t

t = (+13.5 rev)/(18.0 rad/s) = 0.75 - wrong answer

(b) (ω - ω0)/t = α

(0 rad/s - 18.0 rad/s)/0.75 = α - wrong answer

-----------------------------------------------------------------

1. The problem statement, all variables and given/known data

After 10.0 s, a spinning roulette wheel at a casino has slowed down to an angular velocity of +1.70 rad/s. During this time, the wheel has an angular acceleration of -5.05 rad/s^2. Determine the angular displacement of the wheel.

2. Relevant equations

ω^2 = ω0^2 + 2α(θ − θ0)

3. The attempt at a solution

(+1.70 rad/s)^2 = 0 + 2(-5.05 rad/s^2)θ

θ = [(1.70 rad/s)^2]/2(-5.05 rad/s^2) = -0.286 - wrong answer

------------------------------------------------------------------

Please help me, I don't know what I'm doing wrong.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Rotational Kinematics of bicycle breaks

**Physics Forums | Science Articles, Homework Help, Discussion**