You are holding the axle of a bicycle wheel with radius
35.0 cm and mass 1.00 kg. You get the wheel spinning at a rate of
75.0 rpm and then stop it by pressing the tire against the pavement.
You notice that it takes 1.20 s for the wheel to come to a
complete stop. What is the angular acceleration of the wheel?

The angular acceleration of the wheel is -6.54 rad/s²

Explanation:

We'll use the equations of motion for this.

w = 2πf

f = 75 rpm = 1.25 rps = 1.25 rev/s

w₀ = initial angular velocity = 2π × 1.25 = 7.85 rad/s

w = final angular velocity = 0 rad/s

t = 1.2 s

α = ?

w = w₀ + αt

0 = 7.85 + 1.2α

α = 7.85/1.2 = - 6.54 rad/s²

kepler used the data from tycho blahe (his mentor) to construct the laws of planetary motion.

t = 1/400 h   ⇔ 0.0025 h ⇔ 9s ⇔ 0.15 m

any of the answers are correct.