1.) Running on a treadmill is slightly easier than running outside because there is no drag force to work against. Suppose a 60 kg runner completes a 5.0 km race in 15minutes.

Part A. What is this force as a fraction of the runner's weight? Answer is not 0.027

2.)A person with compromised pinch strength in their fingers can only exert a normal force of 6.0 N to either side of a pinch-held object, such as the book shown in (Figure 1) .

Part A. What is the mass of the heaviest book this person can hold onto vertically before it slips out of his or her fingers? The coefficient of static friction of the surface between the fingers and the book cover is 0.65. Answer is not 0.397 kg.

3.) A 27kg loudspeaker is suspended 2.5m below the ceiling by two cables that are each 60? from vertical.

Part A. What is the tension in the cables? Express your answer using two significant figures.