Direction of Velocity If you push a book in the forward direction, does this mean its velocity has to be forward? No, it could be moving backward and you would be reducing that velocity. Fnet ! FAlutia on sled " FSeward on sled $ FKodiak on sledġ2. What is the net force on the sled? Identify east as positive and the sled as the system. Alutia pulls east with a force of 35 N, Seward also pulls east but with a force of 42 N, and big Kodiak pulls west with a force of 53 N. Three confused sleigh dogs are trying to pull a sled across the Alaskan snow. Label all forces with their agents and make the arrows the correct lengths. Free-Body Diagram Draw a free-body diagram of a bag of sugar being lifted by your hand at a constant speed. Yes, you can feel the inertia of either object by using your hand to give either object an acceleration that is, try to change the objects velocity. Inertia Can you feel the inertia of a pencil? Of a book? If you can, describe how. If the same two forces as in the previous problem are exerted on the canoe in opposite directions, what is the net horizontal force on the canoe? Be sure to indicate the direction of the net force.ġ0. Fnet ! 225 N " 165 N ! 3.90#102 N in the direction of the two forces 7. If these forces are applied in the same direction, find the net horizontal force on the canoe. Two horizontal forces, 225 N and 165 N, are exerted on a canoe.
(Ignore air resistance.)Ĭhapter 4 continued page 93 6. A rope lowers a bucket at a constant speed. (The air exerts an upward force on the person.) "yĥ. A sky diver falls downward through the air at constant velocity. (Ignore air resistance.)Ĭopyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Ģ. A rope lifts a bucket at a constant speed. (Ignore any forces due to air resistance.)Ĥ. A flowerpot falls freely from a windowsill. Label all forces with their agents, and indicate the direction of the acceleration and of the net force. For each of the following situations, specify the system and draw a motion diagram and a free-body diagram. The surface provides a force that resists the crate’s motion. A cable pulls a crate at a constant speed across a horizontal surface.
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