A person standing at the edge of a seaside cliff kicks a stone over the edge with a speed of 20 m/s.?
Ok firstly to work out the time of how long it takes for the stone to hit the ground.Im assuming you have done the SUVAT equations right?S = 54U = 0 (this is for free fall so the U is 0)V = -A = 9.81T = -The equation we can use to work out time is:s= 1/2 x a x t²Plug the numbers in:54 = 1/2 x 9.81 x t²108 = 9.81 x t² (brought the 1/2 over and multiplied by 2)11.00 = t² (108 divided by 9.81)3.31 = t (squared 11.00)3.31 seconds.2) What speed? So the impact velocity.You can use the v = u +at equation to work out the impact velocity of free fall with no initial kick of 20m/s.v = 0 + 9.81 x 3.31v = 32.5ms-1 or just 32.5m/sTHIS IS JUST FOR FREE FALL NOW WE NEED TO WORK OUT THE IMPACT VELOCITY WHEN IT IS KICKED AT 20M/S.The easiest way to picture the next part is to draw a horizontal line across your paper signifying the horizontal vector of 20m/s. And then a vertical line down your paper connected to the horizontal way signifying the vertical vector which was 32.5m/s (just a free fall).If you know what im getting at you can see a right angled triangle. Join up the horizontal and vertical lines are you get the hypotenuse which is the impact velocity when the ball or stone is kicked at 20m/s.C² = 20² + 32.5²C² = 1456.25C=38.7m/s or ms-1.Impact velocity is 38.7m/s. 1 week ago its was 3.32s so had to change and plug in but thanks so much!