If the car\'s mass were doubled, its total mechanical energy at the top would: D

Question

If the car's mass were doubled, its total mechanical energy at the top would: Double; Quadruple Remain the same None of the above. When the car's speed is 20m/s. it is at a height (relative to ground level) of: Less than 10 m; Between 10 and 20 m; Between 20 and 30 m; None of the above. If friction and air resistance do a total amount of work of -125,000 J, the speed of the car at the bottom of the ride is: Less than 10 m/s; Between 10 and 20 m/s; Between 20 and 30 m/s; Greater than 30 m/s. Airbags in a car reduce the impact force on the rider during a c because of: The work-energy theorem; Conservation of energy; The impulse-momentum theorem; Conservation of momentum. A 75-kg physics teachers is standing on a frozen lake holding a 5 kg textbook. Suddenly the teacher throws the book away. Use the direction in which the book is moving after being thrown as the positive direction. Questions 18-24 refer to this situation. After the book is thrown, the total momentum of the system book and teacher is: Positive; Negative; Zero. After the book was thrown, the teacher will: Move in the positive direction; Stay at rest; Move in the negative direction. Which object undergoes the greater impulse while the book is being thrown: The book; The teacher; The impulses are equal in magnitude.

Explanation / Answer

14) Total mechanical energy would = double .

15)   Height =   v2/2g

                      =   20 * 20/(2 * 9.8)

     => none of above

16) Greater than 30 m/sec

17) The impulse momentum theorem

18) As, momentum is conserved

=> total momentum of system = zero

19)    As, the book is thrown in positive direction

=> teacher will move in negative direction .

20)   As, impulse = change in momentum

=> impulses are equal in magnitude .

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