8) How do photons help explain the photoelectric effect? A. Changing light frequencies create opposing electric fields that affect electrons.
B. "Packets" of electromagnetic energy eject electrons.
C. Particles with positive charge attract negative electrons.
D. Single particles of light take the place of electrons
that have similar mass and energy.

It's a snowy day and you're pulling a friend along a level road on a sled. you've both been taking physics, so she asks what you think the coefficient of friction between the sled and the snow is. you've been walking at a steady 1.5m/s, and the rope pulls up on the sled at a 32 ∘ angle. you estimate that the mass of the sled, with your friend on it, is 65 kg and that you're pulling with a force of 80 n .