A laboratory cart sits at rest on a level

PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

A 4.0 kg4.0\,\text{kg} laboratory cart sits at rest on a level, frictionless track. Four horizontal forces act on the cart, as listed below, and a fifth unknown horizontal force F⃗5\vec F_5 is also applied so that the cart remains at rest. (a) Resolve each of the four known forces into its north–south and east–west components. Organize your results in a table. (b) Determine the magnitude and direction of the unknown force F⃗5\vec F_5 that must be applied to keep the cart in translational equilibrium. Express the direction as an angle measured counterclockwise from due east. (c) Demonstrate explicitly that the complete set of five forces produces zero net force on the cart. (d) If F⃗2\vec F_2 were increased to 12 N12\,\text N while all other forces (including F⃗5\vec F_5 from part (b)) remained unchanged, predict qualitatively the subsequent motion of the cart. Justify your prediction without performing additional calculations.

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