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Gears are important components in many mechanical devices, from mechanical clock

ID: 1474807 • Letter: G

Question

Gears are important components in many mechanical devices, from mechanical clocks to bicycles. In fact, they are present whenever a motor produces rotational motion.

An example of a simple gear system is shown in the figure. (Figure 1) The bigger wheel (wheel 1) has radius r_1, while the smaller one (wheel 2) has radius r_2. The two wheels have small teeth and are connected through a metal chain so that when wheel 1 rotates, the chain moves with it and causes wheel 2 to rotate as well.

Part A

Let wheel 1 rotate at a constant angular speed _1. Find the ratio (_1)/(_2) of the angular speed of wheel 1 to the angular speed of wheel 2.

Express your answer in terms of any or all of the variables r_1 and r_2.

(_1)/(_2) = ______________

Part B

The rotation of wheel 1 is caused by a torque _1. Find the ratio (_1)/(_2) of the torque acting on wheel 1 to the torque acting on wheel 2.

Express your answer in terms of any or all of the variables r_1 and r_2.

(_1)/(_2) =  ______________

Explanation / Answer


since the two wheels are connected,then the linear speeds are equal


V = R*w

for the large wheel V1 = r1*w1


for the smaller wheel v2 = r2*w2


since v1 = v2

r1*w1 = r2*w2


w1/w2 = r2/r1


B) torque 1 = r1*F1


torque 2 = r2*F2


by newton's third law of motion F1 = F2

then (_1)/(_2) = r1/r2