An object moves along the x axis according to the equation x = 3.85t2 ? 2.00t +
ID: 1917173 • Letter: A
Question
An object moves along the x axis according to the equation x = 3.85t2 ? 2.00t + 3.00, where x is in meters and t is in seconds. (a) Determine the average speed between t = 2.80 s and t = 4.60 s. (b) Determine the instantaneous speed at t = 2.80 s. (c)Determine the instantaneous speed at t = 4.60 s. (d) Determine the average acceleration between t = 2.80 s and t = 4.60 s. (e) Determine the instantaneous acceleration at t = 2.80 s. (f)Determine the instantaneous acceleration at t = 4.60 s. (g) At what time is the object at rest?Explanation / Answer
let us assume, y = yi + vyi + (1/2) ay t2 measuring distances from the top of the well so yi = 0 and we drop the pebble so vyi = 0 so this equation reduces to y = (1/2) ay t2 y = (1/2) ( - 9.8 m/s2 ) (16 s)2 y = - 1 254.4 m That is a very deep "well", indeed! But, maybe, wells were deeper in such prehistoric times. If we had used the approximation that ay = - g = - 10 m/s2, then our value would have been y = - 1 280 m