Class Management | Help Chapter 9- Linear Momentum Begin Date: 10/26 2017 10:00:
ID: 1774915 • Letter: C
Question
Class Management | Help Chapter 9- Linear Momentum Begin Date: 10/26 2017 10:00:00 AM Due Date: 11/7/2017 11:59:00 PM End Date: 117/2017 11:59:00 PM (10%) Problem 9: Two cars collide at an icy intersection and stick together afterward. The first car has a mass of 1100 kg and is approaching at 5 m/s due south. The second car has a mass of 650 k and is approaching at 19.5 m/s due west. 33% Part (a) Calculate the magnitude of the final velocity, in meters per sccond, of the cars. Grade Summary Potential 100% sind) cos() tanQ | (1)17| 89 cotan asinO acos0 atan acotansinh coslanh)colanh Snhmissions Attempts remaining: 6 (1 % perttempt) delailed view Dcgrces Radians Submiit Hint Hints: 0% deanction per hint. Hints remaining: 2 Feedback: 1 % dednation per feedhack. 33% Part (b) Calculate the direction ofthe final velocity, in degrees south of west, of the cars. 33% Part (c) What is the changc in kinetic cncrgy. in Joules, for the collision? This cncrgy gocs into dcform ation of the cars.)Explanation / Answer
(a) Applying momentum conservation,
(1100 x -7.5j) + (650 x - 19.5i) = (1100 + 650) vf
vf = -7.24i - 4.71j
magnitude = sqrt(7.24^2 + 4.71^2) = 8.64 m/s
(b) theta = tan^-1(4.71/7.24) = 33 deg
(c) Ki = (1100 x 7.5^2 / 2)+ (650 x 19.5^2 / 2)
= 1.545 x 10^5 J
Kf = (1100 + 650) (8.64^2)/2 = 0.653 x 10^5 J
K_lost = Kf - Ki = - 89 x 10^3 J