a physics student walks 100 meters in 80 seconds. the student stops for 30 seconds, and then walks 200 meters farther in 90 seconds. what is the average speed of the entire walk?

Using the free-body diagram, calculate the net force acting on the sled. is the sled in a state of dynamic equilibrium?

An alpha particle with kinetic energy 12.5 mev makes a collision with lead nucleus, but it is not "aimed" at the center of the lead nucleus, and has an initial nonzero angular momentum (with respect to the stationary lead nucleus) of magnitude l = p0 b, where p0 is the magnitude of the initial momentum of the alpha particle and b=1.40×10−12 m. (assume that the lead nucleus remains stationary and that it may be treated as a point charge. the atomic number of lead is 82. the alpha particle is a helium nucleus, with atomic number 2.) what is the distance of closest approach?

The receptor cells that convert light energy into neural signals are called