N6T.2 Which of the following pairs of forces are third-law partners? Answer T if the two forces described are third- law partners, F if they are not. (a) A thrust force from its propeller pulls a plane forward; a drag force pushes it backward. (b) A car exerts a forward force on a trailer; the trailer tugs backward on the car. (c) A motorboat propeller pushes backward on the water the water pushes forward on the propeller. (d) Gravity pulls down on a person sitting in a chair; the chair pushes back up the person. on

5. You are messing around with two textbooks and you place one on top of the other. You lift the lower book at one side to make a ramp. Draw a free-body diagram for the upper book while the books are still ying flat on the table.- a. There are two forces on the book. top b. Draw a free-body diagram for the upper book while the lower book is at an incline. There are three forces on the top book, now. What happens to the magnitude of the normal force exerted on the upper book once the lower book is lifted? Does it get bigger, smaller, or stay the same? с.

Dana pushed a wooden crate that was at rest on the floor. The crate moved when she ap- plied 49 N of force. If the friction coefficient was 0.1, what was the weight of the crate? 4.9 N B. 490 N 49 N D 0.49 N

18. A child sits on a sled at the top of a hill, the hill makes an angle of 20° with the horizontal. The child's mass is 40kg. Use us = .1 and 4.03 a. b. Draw a free body diagram for this system. Does the child accelerate down the hill? *i.e., check that the coefficient of static friction is vercome by the component of the childs weight in the direction the child would accelerate. If they do, what is their acceleration? *use coefficient of kinetic friction in sum of the forces balance if the child moves.

while tom pushes a 40 kg box in horizontal direction along the classroom floor with a 100 N force, the box is moving in a straight line with constant speed of 0.5 m/s. Ignor air resistance when answering the questions below. a. Write down as much information as you can about the main horizontal forces exerted on the box ( names, directions and if enough information is given, numerical values). b. Write down as much information as you can about the main vertical forces exerted on the box (names, directions, and whenever possible, if enough information is given, numberical values). c. How far did the refrigerator move during those 3 seconds? Explain d. What was the refrigerator's acceleration during that time? Explain