Aparticle's trajectory is described by x =(1/2t3? 2t2)m and y =(1/2t2? 2t)m, where t is in s, what is the particle's speed at t=4.5s ?

Use the empirical rule. the mean speed of a sample of vehicles along a stretch of highway is 70 miles per hour, with a standard deviation of 4 miles per hour. estimate the percent of vehicles whose speeds are between 66 miles per hour and 74 miles per hour. (assume the data set has a bell-shaped distribution.)

Fill in the blank. the number of each type of element in the compound (other than 1) is represented by a small number to the right of the element symbol.

For the car in the picture ,in which direction is the normal force? -into the screen -down -out of the screen -up