Convection currents within earth's core and mantle transfer large amounts of heat when
a. hotter, less dense rock rises and cooler, more dense rock sinks
b. cooler, less dense rock sinks and hotter, more dense rock rises
c. hotter, less dense rock sinks and cooler, more dense rock rises.
d. cooler, less dense rock rises and hotter, more dense rock sinks.

What is the weight of a feather (mass = 0.0001 kg) that floats through earth's and the moon's atmospheres?

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 .

Two cans on a sunny window one black and the other white construct and explanation of the effect of sun will have on both cans over a two hour period?