object is tied to the end of a cord and it is turning in horizontal eircle of radius 1.20 em at t 5. A 200-g constant 3 rev/s (a) Calculate the centripetal acceleration of the object (b) Find the tension in the cord 6. The bob of a pendulum 90 em long swings through a 15-em are, as shown below Determine the angle ? in degrees. 7. A 75-Kg firefighter climbs a flight to stairs of 2800 centimeter high. How much work does he do? Solution 5) angular speed = w = 3 rev/s = 3*2pi = 18.84 rad/s centripetal acceelration ac = v^2/r = (rw)^2/r = rw^2 ac = 1.2*10^-2*18.84^2 = 4.26 m/s^2 tension T = ma = 0.2*4.26 = 0.852 N 6) arc length = r*theta theta = arc length/radius theta = 15/90 = 0.167 rad theta = 0.167*180/3.14 = 9.57 degrees 7) work = potential energy w = mgh = 75*9.8*28 = 20580 J .

1. object is tied to the end of a cord and it is turning in horizontal eircle of radius 1.20 em at t 5. A
200-g constant 3 rev/s (a) Calculate the centripetal acceleration of the object (b) Find the tension
in the cord 6. The bob of a pendulum 90 em long swings through a 15-em are, as shown below
Determine the angle ? in degrees. 7. A 75-Kg firefighter climbs a flight to stairs of 2800
centimeter high. How much work does he do?
Solution
5) angular speed = w = 3 rev/s = 3*2pi = 18.84 rad/s
centripetal acceelration
ac = v^2/r = (rw)^2/r = rw^2
ac = 1.2*10^-2*18.84^2 = 4.26 m/s^2
tension T = ma = 0.2*4.26 = 0.852 N
6) arc length = r*theta
theta = arc length/radius
theta = 15/90 = 0.167 rad
theta = 0.167*180/3.14 = 9.57 degrees
7) work = potential energy
w = mgh = 75*9.8*28 = 20580 J