A 60672 g woman in an elevator is accelerating upward at a rate of 120:54 cm/s2. Convert all given quantities into SI units. Show conversion factors. Determine the normal force exerted on the woman's feet by the oor. (Use g = 9:8m=s2) Does the normal force remain the same if the elevator is accelerating downward with the same magnitude of acceleration?

2) In space, away from gravitational influences, a small 750 kg rocket's main engine produces a force of 1500 N. a) If it begins from rest and fires this engine for 18.0 s, how far does it travel? b) It then also fires a side thruster that produces a force perpendicular to the main engine. If the resulting acceleration is 2.10 m/s², what is the magnitude of the force the side thruster produces? c) What is the direction of the acceleration in part b, measured as an angle from the original direction of the velocity?

*69. A damp washcloth is hung over the edge of a table to dry. Thus, part (mass = mm) of the washcloth rests on the table and part (mass = m) does not. The coefficient of static friction between the table and the wash- cloth is 0.40. Determine the maximum fraction [ma/(mon + moa)] that can hang over the edge without causing the whole washcloth to slide off the table.

answer Q 2

L A B A m m q 9 Two point charges (each of mass m and charge q),A and B, are suspended by very thin threads as shown above. a. Which of the diagrams below represents the free body diagram for object A (Here is FBA is the electrostatic force exerted by object B on object A, WA is the weight of object A, TA is the string tension, and N is the normal force)? O O O W FBA YA ap FBA WA TA TA O None of the above. y I 1. FBA X

7. A car is right on the verge of sliding as it speeds around a level circular track. The radius of the circular track is 21 m, and the coefficient of static friction between the car's tires and the track is 0.7, while the coefficient of kinetic friction is 0.56. What is the speed of the car?

71. The following situations show a car towing a trailer. Rank the difference in forces between the force that the car applies on the trailer FcT and the trailer on the car FT/c from largest to smallest. D A a=2 m/s? a = 4 m/s? m = 2000 kg v = 20 m/s a = 0 a = 0 m = 4000 kg v = =20 m/s m = 1000 kg v= 20 m/s = 10 m/s !! .m = 1000 kg v c. AF, > AF, > AF. = AF, d. AF = AF, = AFc = AF, AF, = AF, > AF, > AF. а. D В В D B b. AF, > AF, = AF. = AF, D В B

An ice skater is traveling in a straight, horizontal line on the ice with a velocity of v = 7.5 m/s in the positive x-direction. The coefficient of kinetic friction between the skates and the ice is μk = 0.23.  v=7.5 m/s uk= 0.23   Using the expression for normal force,write an expression for the skaters acceleration in the x-direction, a

Determine the force Q-> when the block moves with constant velocity. Express your answer in vector form.

1. You are working as a letter sorter in the Post Office. Postal regulations require that employees' footwear must have a minimum coefficient of static friction of 0.5 on a specified tile surface. You are wearing athletic shoes for which you do not know the coefficient of static friction. In order to determine the coefficient, you imagine that there is an emergency and start running across the room. You have a co-worker time you, and find that you can begin at rest and move 4.23 m in 1.20 s. If you try to move faster than this, your feet slip. Assuming your acceleration is constant, does your footwear qualify for the postal regulation? 7