Question

please answer 12-14

12) The graph shows the force on an object as it moves a distance x. What is the work done by the force as the object moves from 2.0 m to 8.0 m? F(ND A) 35 ) B) 48 ) C) 50 J D) 52) E) 60 x (m) 13) A car traveling at 30 mph skids to a stop in 60 meters. If an identical car traveling at 60 mph skids to a stop under the same conditions, what distance would it travel? A) 340 m B) 310 m C) 260 m D) 240 m E) 190 m 14) A 2000 kg car accelerates from rest to a velocity of 40 m/s in 5.0 seconds. The brakes are applied, and the car is brought to a stop (without sliding). The magnitude of the work done by the friction in the brakes is A) 1.0 106 B) 1.2 106 C) 1.6 106. D) 2.1 106). E) 2.5 106. 15) A 2,00 kg pendulum bob on a string 3.00 m long is released with a velocity of 1.00 m/s when the support string makes an angle of 30.0 degrees with the vertical. What is the tension in the string at the highest point of its motion? A) 30.8 N B) 275 N C) 20.1 N D) 16.6 N E) 105N

Answer 1

13- The work done from am to om is the area under the cusue. W=Fdx W=(@N.) [8m-am] (W = 405. Using Newton's tyd equation of motion, -205 0 = (30)2 - 90.(60) a = (30) 2x60 Using Newton's filed equation of motion, U2 = u Las 0 = (60) 2 - 2x (30)2 x S 2X60 s=foot = 240m The work done is equal to the change in KE. W = K.E. - KiEig W = 1 m² - 1 mu? W = 4 x 2000 x [40)2-(0)] W= 1.6X1065.