PhysicsVelocity after Displacement worksheet assistance

Question #2

• With a cruising speed of 2.30 × 103 km/h, the French supersonic passenger jet Concorde is the fastest commercial airplane. Suppose the landing speed of the Concorde is 20.0 percent of the cruising speed. If the plane accelerates at –5.80 m/s2, how far does it travel between the time it lands and the time it comes to a complete stop?• Its landing speed is 20% of cruising speed (ie .2 * 2300 km/h)• vi = 460 km/h [must change to m/s so divide by 3.6] = 127.8 m/s• a = –5.80 m/s2

• X = ?

Question #2, continued

• It is not asking for how much time AND I know that it came to a stop• I’ll use: vf

2 = vi2 + 2ax

• 0 = (127.8)2 + 2(-5.80)x• 0 = 16332.84 – 11.6x• -16332.84 = -11.6x• 1408 m = x

Question #5

• The skid marks left by the decelerating jet-powered car The Spirit of America were 9.60 km long. If the car’s acceleration was –2.00 m/s2,what was the car’s initial velocity?• x = 9.60 km = 9600 m• vi = ?• vf = 0 m/s• a = -2 m/s2

Question #5, continued

• vf2 = vi

2 + 2ax• 0 = vi

2 + 2(-2)(9600)• 0 = vi

2 + -38400• 38400= vi

2

• 196 m = vi

Question #10

• The lightest car in the world was built in London and had a mass of less than 10 kg. Its maximum speed was 25.0 km/h. Suppose the driver of this vehicle applies the brakes while the car is moving at its maximum speed. The car stops after traveling 16.0 m. Calculate the car’s acceleration.• vi = 25 km/h divided by 3.6 = 6.94 m/s• vf = 0 m/s• x = 16 m• a = ?

Question #10, continued

• vf2 = vi

2 + 2ax• 0 = 6.94 2 + 2a(16)• 0 = 48.16 + 32a• -48.16= 32a

• -1.51 m/s2 = a