11. If you hold a negatively charged plastic rod up to a ball hanging on a thread, and the ball moves towards the rod, the ball
a. has no charge
b. has no matter
c. is positively charged
d. is negatively charged

The variables for this experiment include mass, volume and the materials in the various balls, as well as their densities. in part iii, you will be investigating the questionable baseball. use the drop-down menus to complete the sentences and identify the independent and dependent variables. in part iii, the independent variable, the one that is intentionally manipulated, is . in part iii, the dependent variable, the one that you measure the response in, is

A23 kg log of wood begins from rest, 300 m up a sluice (a water track used to transport logs, think of it as an inclined plane with negligible friction) inclined at 20° to the horizontal. after it reaches the flat waterway at the bottom it collides elastically with a 100 kg block of wood initially at rest near the base of the incline. (a) how long does it take the 23 kg log to travel down the incline? (b) what is the speed of the 23 kg log at the bottom of the incline? (c) what are the velocities of both blocks of wood after the collision? (d) what is the total kinetic energy before the collision? (e) what is the kinetic energy of the 23 kg log after the collision? (f) what is the kinetic energy of the 100 kg block of wood after the collision? (g) what is the total kinetic energy after the collision? (h) compare the total initial and total final kinetic energies. is this consistent with what you would expect for elastic collisions? explain!

Ameter stick is pivoted at the 0.50-m line. a 3.0-kg object is hung from the 0.15-m line. where should a 5.0-kg object be hung to achieve equilibrium (the meter stick oriented horizontal and motionless)?