Physics Review PDF

Physics Review Acceleration: The rate of change of velocity Displacement: Distance between two measurements with direction OR Distance with direction. What's the difference between average velocity and average speed? - Average speed is how fast something moves, while average velocity is bo...

Physics Review Acceleration: The rate of change of velocity Displacement: Distance between two measurements with direction OR Distance with direction. What's the difference between average velocity and average speed? - Average speed is how fast something moves, while average velocity is both speed and direction. OR Speed is how fast velocity has direction. If a car accelerates from 4 m/s to 8 m/s. What is the change in velocity? - Acceleration: Vf -- Vi = 8 m/s -- 4 m/s = 4 m/s. A car travels a distance of 70 km in 2 hours. What is the average speed? - Average speed: Total distance over Total time. 70 km over 2 hours = 35 km/h. A construction worker accidentally drops a brick from a high scaffold. What is the velocity of the brick after 4 seconds? And how far does the brick fall during this time. - G:10 m/s2 Vi: 0 t: 4s 0-10(4) = -40 m/s A person can walk at a speed of 1.5 meters/second. How far will he walk in 4 minutes? - Distance: Speed x Time. Convert 4 min into sec. 4 x 60 = 240 sec x 1.5 = 360 m/s A runner finishes a 100-meter dash in 8 seconds. Determine his average speed. - Average speed: Total distance over total time. 100 meters over 8 seconds = 12.5 m/s An aircraft starts from rest and accelerates on a straight runway at a rate of 8 m/s2 for 400 meters. How much time does this take? - D= Vi t + 1 over 2 at2. D= distance vi = 0 a = 8 m/s2 400 = 1/2 x 8 x t2 -\> 400 = 4t2 -\> t2 = 400 over 4 = 100 -\> t=square root100 = 10 seconds. A test car accelerates from rest at 4 m/s2 over the course of 200 m. How fast does the car go at the end of this acceleration? - V2f = v2i + 2ad = vf ? vi = 0 a = 4 m/s2 d= 200m v2f = 2x 4 m/s2 x 200 m v2f = 8x 200 = 1600 vf = square root1600 = 40 m/s A rocket is launched vertically upwards from the ground. The rocket travels with uniform acceleration from rest. After 8 seconds the speed of the rocket is 120 m/s. Calculate the acceleration of the rocket. - Acceleration: Vf -- Vi over t. Vf=120 m/s Vi=0 m/s t=8s 120 -- 0 over 8 -\> 15 m/s2 Can displacement be negative? Explain why. - Yes, displacement can be negative because it shows the change in position. Final -- initial. If the man and the ball travels 90 min in 9 sec. What is the average speed? - Average speed = Total distance over total time. 90 m over 9 s = 10 m/s. If an object moves 5 meters to the right and 3 meters to the left what is the total distance? - Distance to the right = 5m Distance to the left 3m. 5 + 3 = 8 meters. A car travelling freeway at 6 m/s when the driver sees traffic 100m ahead he stops. What's the acceleration? - V2f = V2i + 2ad. Vf =0 Vi= 6 a =? D= 100m -\> 0=6m/s2 + 2a (100m) 0=36 m2/s2 + 200a -\> 36m2/s2 + 200a -\> 200a=-36m2/s2 a = -36m2/s2 over 200 -\> a= -0.18 m/s A car moving to the right at 20 m/s accelerates to the right at 3/ms2 for 14 meters. What is the car's velocity after the acceleration period? - V2f = V2i + 2ad -\> Vf=? Vi = 20 a= 3 d= 14m -\> 20m/s2 = 400 m2/s2 -\> 2x3m/s2 x 14m = 84 m2/s2 -\> 400m/s + 84 m/s -\> Vf= square root484m/s = 22m/s If two boats went opposite sides in 10 km/h. What will be the same? Distance, length or velocity? Velocity, because it includes speed and direction and because their speeds add up when moving in opposite directions. Multiple choice answer; A C D C C A C A A A Equations : How long = Second - Acceleration = Vf -- Vi Change in acceleration Vf - Vi How fast = Vf - Velocity = d Change in velocity : Vf -- Vi - How far = Distance; Speed x Time Only m not m/s - Displacement = Velocity x Time Meter - Speed = Total distance M/S Average speed we don't have to convert and it's m/s