PHSCS 121 Final Exam Questions All Solved

PHSCS 121 Final Exam Questions All Solved a driver who is protected by an air bag during a head-on collision is less likely to be seriously injured than an unprotected driver. this is because the airbag - Answer -increases the time interval over which the impulse is experienced 9cm a bullet moving horizontally strikes and sticks in a block of wood that is free to move on the horizontal, level, frictionless surface. the block has a much greater mass than the bullet. what becomes of most of the momentum of the bullet - Answer -it becomes total momentum of the block plus the bullet 9cm block A is traveling due north with a velocity of 10m/s. block B is traveling due east with a velocity of 1m/s. block A has 10 times the mass of block B. the two blocks stick together after the collision. after the collision the two blocks - Answer -travel slightly east of north 9cm a body is made up of multiple parts that are attached to each other by several compressed springs. it has been shot from a cannon and at the peak of its trajectory the springs are released, causing the parts to fly apart. the center of mass of the two parts - Answer -continues along the same parabolic path as before 9cm a rocket fully loaded with fuel is fully loaded with fuel is sitting in space far from any other body. the engine is started and the rockets starts to spew exhaust gases out of the back of the engine. which of the following explains what happens? - Answer -the momentum of the exhaust gases must be equal to the momentum gained by the rocket. 9cm a driver who is protected by an airbag during a head on collision is less likely to be seriously injured than an unprotected driver. this is so because the airbag - Answer -increases the time interval over which the impulse is experienced (impulse and change in KE are unchanged by the presence of the airbag. the driver still has to go from initial velocity to zero velocity, which determines his change in KE and his impulse. making collision more elastic would be a bad thing, as it would require the driver to rebound, which would increase the impulse) 9q imagine you are designing a small car and you want to make it as safe as possible. there are two ways that you can design the car for a collision. one is to make it so that the car will crumple up and come to rest along with the other vehicle. the other method is to make the car very rigid so that it will bounce off of the other vehicle. which method will be safer to use - Answer -the crumple method, because the force experiment by the passengers will be less in this case (the force will be less because the same impulse is applied over a longer period of time, making it so that the force can be less) 9q [[A Volkswagen bug is moving to the right with a speed of 20 m/s. A large SUV is moving to the left at a speed of 20 m/s. The SUV has a mass three times that of the small car. They have an totally inelastic head-on collision in an intersection. There are two passengers in each vehicle, one seat-belted and the other not seat-belted. All the passengers weigh the same. The non-seat-belted passengers both collide with the dashboard of their respective cars. Use the following codes to refer to each of the passengers: SB = SUV, belted SN = SUV, non-belted VB = Volkswagen, belted VN = Volkswagen, non-belted]] rank magnitude of IMPULSE experienced by four passengers in this collision from SMALLLEST to LARGEST. - Answer -SB=SNVB=VN (both passengers in each car experience the same impulse, since it is equal to the change in the momentum. this requires from sb=sn and vb=vn. after the collision the two cars are moving in the direction of the suv at 10 m/s. this means that the passengers in the suv experienced a change in velocity of 10m/s while the passengers in the bus experienced a change in velocity of 30 m/s.