Eli rolled a ball down the cement sidewalk as hard as he could. the ball rolled for less than a minute before it came to a stop. what force acted to slow and finally stop the ball? a. friction, acting in the same direction as the motion of the ball b. the normal force, pushing upward on the ball c. friction, acting in opposition to the motion of the ball d. the normal force, pulling downward on the ball

An engineer designs a roller coaster so that a car travels horizontally for 162 ft, then climbs 127 ft at an angle of 31.0° above the horizontal. it then moves 127 ft at an angle of 46.0° below the horizontal. if we take the initial horizontal motion of the car to be along the +x-axis, what is the car's displacement? (give the magnitude of your answer, in ft, to at least four significant figures and give the direction of your answer in degrees counterclockwise from the +x-axis.)

The graph describes the motion of an object. the object moves with from a to b. it from b to c. it moves with from c to d.

Two polarizers are oriented at 40∘ to each other and plane-polarized light is incident on them. if only 16 percent of the light gets through both of them, what was the initial polarization direction of the incident light?