A wheel slows down uniformly and comes to rest in 15 seconds. It ...

[Lobcity]

A wheel slows down uniformly and comes to rest in 15 seconds. It is rotating initially at 2.0 revolutions per second and has a diameter of 50.cm.
 
  (a) What was the centripetal acceleration at the instant when it was rotating initially?
  (b) What was the tangential acceleration?

Question 2

Mathilda collects photoelectric data in her physics laboratory. She measures a stopping potential of 5.82 volts for radiation of wavelength 100. nm, and 17.99 volts stops 50.0 nm.
 
  (a) What is the work function for the material in eV?
  (b) From her data one determines Planck's constant to be what?

[emily12345]

Answer to Question 1

(a) 39. m/s2
(b) -0.21 m/s2

Answer to Question 2

(a) 6.70 eV
(b) 6.50  10-34 J-s

[Lobcity]

Gracias!

[debra928]

Thanks for the timely response, appreciate it