A ball with a mass of 200 g is tied to a light string that has a length of 2.00 m. The end of the string is tied to a hook, and the ball hangs motionless below the hook. Keeping the string taut, you move the ball back and up until the string makes an angle of 27.0° with the initial vertical position. You then release the ball from rest, and it oscillates back and forth, pendulum style. Use g = 9.80 m/s2. (a) If we neglect air resistance, what is the highest speed the ball achieves in its subsequent motion? (b) Resistive forces eventually bring the system to rest. Between the time you release t

Question

anonymous · Answer

(b) Resistive forces eventually bring the system to rest. Between the time you release the ball and the time the ball comes to a permanent stop, how much work do the resistive forces do? (Use the appropriate sign.)

fifciol · Answer

|dw:1383080701721:dw|
a)$$mgh=\frac{ mv^2 }{2 }$$
b)
the amount of work done by resistive forces is simply the initial energy that is lost, but the direction of these forces is opposite to the direction of motion so work is negative
W=-mgh  or W=-mv^2/2