Unit 3 Exam

A 60 kg ice skater holding a 20 kg box is moving with a velocity of 4 m/s. She needs to throws the box in front of her to come to a stop before she reaches a hole in the ice. How fast does she need to throw the box?

• 5.3 m/s

• 4.0 m/s

• 10 m/s

• 16 m/s

Tags

NGSS.HS-PS2-1

NGSS.HS-PS2-2

A 1 kg cart moving at 4 m/s collides inelastically with a 2 kg mass which is initially at rest. Which of the following statements is not true about the momentum of the two carts?

• The two carts have the same velocity after the collision

• The total kinetic energy of the system is the same before and after the collision

• Before the collision, the total momentum was equal to the momentum of the 1 kg cart

• After the collision, the 2 kg cart has more momentum than the 1 kg cart

Tags

NGSS.HS-PS2-2

A railroad flatcar of mass rolls to the right with a momentum of 20,000 kg*m/s and collides with another flatcar that is rolling to the left with a momentum of -15,000 kg*m/s. What is the total momentum of the two flatcar system after they collide?

• 5,000 kg*m/s

• 10,000 kg*m/s

• 20,000 kg*m/s

• 35,000 kg*m/s

Tags

NGSS.HS-PS2-2

Which cart has less mass?

• Cart A because it changed its velocity less

• Cart B because it changed its velocity less

• Cart A because it changed its velocity more

• Cart B because it changed its velocity more

Tags

NGSS.HS-PS2-1

A 1 kg rock is dropped off a 90 m high cliff. After falling 20 m, the kinetic energy of the rock-Earth system is approximately -

• 20 J

• 200 J

• 700 J

• 900 J

Tags

NGSS.HS-PS3-2

A 0.6 kg spring with a spring constant of 1200 N/m is compressed 5.0 cm from its equilibrium position by a mass. How much energy is stored in the spring-mass system? (Hint! You need to convert cm to meters!)

• 1.5 J

• 3.0 J

• 3,000 J

• 15,000 J

Tags

NGSS.HS-PS3-1

Two physics students conduct a recoil experiment. The two carts above start at rest. If the final momentum of cart B is -2.4 kg*m/s and momentum was conserved in the recoil, what is the final momentum of cart A?

• -2.4 kg*m/s

• 0 kg*m/s

• 2.4 kg*m/s

• It is not possible to determine with the information provided

Tags

NGSS.HS-PS2-2

While testing his archery skills, Robin Hood shoots an arrow at an apple which is at rest. The 0.2 kg arrow has a velocity of 40 m/s and sticks to the apple as they collide. If the final velocities of the arrow and apple are both 10 m/s, what is the mass of the apple?

• 0.2 kg

• 0.4 kg

• 0.6 kg

• 0.8 kg

Tags

NGSS.HS-PS2-2

A rocket, like the one in the diagram below, operates by using engines to shoot exhaust gases down towards the ground. What is true about the forces acting on the rocket?

• The force of gravity on the rocket must be equal to the force of the exhaust gasses on the rocket

• The force of the exhaust gases on the rocket will be equal to the force of the rocket on the exhaust gases, but in the opposite directions

• The force of the exhaust gases on the rocket must be greater than the force of the rocket on the exhaust gases

• The force of gravity on the rocket must be greater than the force of the exhaust gasses on the rocket

Tags

NGSS.HS-PS2-1

NGSS.HS-PS2-4

The diagram above shows two different trials conducted with equal masses. In Trial 1, the mass is released from the top of ramp and slides down to the ground before colliding with a spring. In Trial 2, the mass is released from the same height and falls onto an identical spring. In both trials there is no friction.

In which trial will the spring compress a greater distance?

• Trial 1, because more of the initial energy of the initial energy of the block-Earth-spring system will be converted into the elastic potential energy of the block-Earth-spring system.

• Trial 2, because the force of gravity on the mass will cause the mass to exert a greater force on the spring.

• The spring will compress by the same distance in both trials since the total energy of the block-Earth-spring system must be conserved.

• Trial 1, because there is more distance for the block to gain kinetic energy

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2