a 20-lb rests on a plane that is inclined at 30° above the horizontal. the height of the plane increases from left to right. the gravitational force acting on the block is make an illustration and work with 2-d vectors to answer the following: (a) what is a unit vector that points down the plane (parallel to the plane)? call (b) what is the force vector f (the magnitude of f is 20 lbs, the weight of the block.) (c) how much of f points in a direction that is parallel to the plane? compute this as the orthogonal projection of f onto ü. (d) how much of f points in a direction that is normal to the plane? compute this as n = f-proj f

Explain the difference between each pair of concepts. a. frequency and relative frequency b. percentage and relative frequency a. select the correct choice below. a. frequency is the total number of observations in a data set. relative frequency is the number of times a particular distinct value occurs. b. frequency is the number of times a particular distinct value occurs. relative frequency is the ratio of the frequency of a value to the total number of observations. c. frequency is the total number of observations in a data set. relative frequency is the ratio of the number of times a particular distinct value occurs to the frequency. d. frequency is the number of times a particular distinct value occurs. relative frequency is the ratio of the frequency of two different values.

Sound travels slower in colder air that it does in warmer air. make a claim about the effect of air temperature on the speed of sound. support your claim with evidence

First answer marked as brainiest which is the correct equation describing the first law of thermodynamics? a) when the internal energy of a system changes, it equals the amount of heat added plus the work done. b) when work is done by the piston, it is equal to the heat added plus the change in internal energy of the system. c) when heat is added to the system, it is equal to the amount of work done by the piston plus the change in internal energy of the system.