13. In a Millikan's oil drop experiment a drop is observed to fall with a terminal speed 1.4mm/s in the absence of electric field. When a vertical electric field of 4.9x10v/m is applied the droplet is observed to continue to move downward at lower terminal speed 1. 71 mm/s. calculate the charge on the drop (Density of oil = 750kg/m3, viscosity of air=1.81 x 10^-5 kg/ms ,density of air=1.29 kg/m3) ​

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 .