A girl, moving at 8 m/s on in-line skates, is overtaking a boy moving at 5 m/s as they both skate on a straight path. The boy tosses a ball backward toward the girl, giving it speed 12 m/s relative to him. What is the speed of the ball relative to the girl, who catches it? (a) (8 1 5 1 12) m/s (b) (8 2 5 2 12) m/s (c) (8 1 5 2 12) m/s (d) (8 2 5 1 12) m/s (e) (28 1 5 1 12) m/s

Torque Torque ● The tendency of a force to rotate a body about some axis ● The same force will be a lot more effective at rotating an object such as a nut with a wrench, or a door opened at the handle instead of a hinge. ● The units of torque are: ○ [τ] = [r][F] = Nm Reformatting Newton’s Second Law ● τ = Iα More Torque ● τnet τ1+ τ2+ ... ● Counterclockwise is positive Examples ● A meter stick (1kg) has a pivot in the center and a two 2 kg masses are located at x = 0.3m to the right of the pivot and y = 0.4m to the left of the pivot. Find the net torque. ● ● A 2-m-long board weighing 50 N extends out over the edge of a table, with 40% of the board’s length off the table. How far beyo