To calculate the density of a substance, what 2 properties do you need to know?

Why does karst topography exist in some geographic location? a. few climates have enough oxygen b. most regions have rock layers other than limestone c. in most regions, the soil is too thin d. the water is too acidic enough in most places

The first law of thermodynamics is as follows: ∆u=q-w , which means in a system is equal to added, minus done by the system. the units for these variables are in .

1) a child holds two dogs on two separate leads. the dogs are pulling in different directions. one is pulling a force of 20n north and one is pulling 15n eastwards. calculate the resultant force on the child. state the direction. (use the parallelogram of forces) 2) a force of 20n acts horizontally on an object. a second force of 5n acts at 60 degrees to the first one. calculate the resultant force. worth 20 points, need answers asap with method you x