A car falls of a ledge and drops to the ground in 0.5 s. Let g= 10 ms-2 a. What is its speed on touching the ground? b. What is its average speed during 0.5s? c. How high is the ledge from the ground?
Given, time taken=0.5s g=10ms−2 As the car is under free fall, the initial speed is zero. (a) Under free fall, u=0 a=g v=u+at v=0+10×0.5 v=5ms−1 (b) Average speed = 2u+v=20+5=2.5ms−1 (c) From newton's equation of motion, As u=0, h=ut+21gt2 When h is the height, t is the time of free fall, g is the acceleration due to gravity. Putting the values in the above equation, we get h=21×10×(0.5)2=5×0.25=1.25m
