A police car in hot pursuit goes speeding past you. While the siren is approaching, the frequency of the sound you hear is 5500 Hz. When the siren is receding away from you, the frequency of the sound is 4500 Hz. Use the Doppler formula to determine the velocity of the police car. Use vsound=330 m/s. What is the velocity v of the police car ?

Awater balloon launcher uses an elastic band with a spring constant of 115 n/m to use thee launcher you stretch thee band back with a balloon n it the water balloons have a mass of 1.3 kg a) if you stretch the band by 0.8 m, what elastic force will the band exert? b) with the band stretched 0.8 m, how much elastic potential energy is stored in the spring? c) if you release the band, it pushes forward. what is the kinetic energy of the balloon when it reaches the natural length of the band? d) what is the speed of the balloon when it reaches the natural length of the band?

Mechanical energy is when there are no forces causing an object to lose energy. a. increased b. conserved c. decreased d. doubled i need this answer ! .

Aball is rolled uphill a distance of 5 m before it slows, stops, and begins to roll back. the ball rolls downhill 9 m before coming to rest against a tree. what is the magnitude of the balls displacement? a. 4 meters b. 9 meters c. 14 meters d. 45 meters