The peripheral speed of the tooth of a 10-in.-diameter circular saw blade is 170 ft/s when the power to the saw is turned off. The speed of the tooth decreases at a constant rate, and the blade comes to rest in 11 s. Determine the time at which the total acceleration of the tooth is 130 ft/s2.

10.5 s      

Explanation:

Initial tangential speed,

Final tangential speed,

Time in which it comes to stop,

Diameter, d = 10 in = 0.83 ft

so, radius r = 0.415 ft

Tangential acceleration,

Total acceleration of the tooth is

so,

b. lifting dumbbell weight at 20-degree angle from the body after a 45-degree angle