Work, Power, Momentum, and Collisions

Work and Energy

100

This must be true for work to be done

A force must cause an object to move in the direction of the force

200

When a ball that is thrown upward reaches its highest point, its velocity is this

What is zero?

300

The law of conservation of energy is true as long as this force is not present

What is friction?

400

The amount of elastic potential energy stored when a spring with k = 200 N/m is compressed 0.40 m (EPE = (1/2)kx²)

What is 16 J?

500

The amount of work that is done when a 20 N force moves and object 2.5 m in the direction of the force (W = Fd)

What is 50 J?

Energy and Power

100

This happens to an object's speed when its kinetic energy is quadrupled (KE = (1/2)mv²)

What is it is doubled?

200

The gravitational potential energy of a 5.00 kg block at the top of 2.00 m ramp (GPE = mgh)

What is 98.1 J?

300

Power can be described as the rate of doing this

What is work?

400

This type of energy is present if an object is in a position from which it could move

What is potential energy?

500

This type of energy is present when an object is moving

What is kinetic energy?

Momentum and Impulse

100

Impulse is equal to a change in this quantity

What is momentum?

200

Airbags reduce injury by doing this

What is increasing the time of the impulse, so that the force is decreased?

300

The law of conservation of momentum states this

What is the total momentum is the same before and after a collision or in other words total momentum remains constant?

400

The units for momentum

What are kgm/s?

500

Increasing the stopping time in a collision will cause this to decrease (I = Ft)

What is the force?

Collisions

100

The final velocity of a 1500 kg car traveling at 25 m/s that collides and sticks to a 750 kg car that was at rest (v_f = [(m₁v_1i + m₂v_2i)/(m₁ + m₂)]

What is 17 m/s?

200

Mechanical energy is only conserved in this type of collision

What is an elastic collision?

300

This quantity is conserved in all collisions

What is momentum?

400

A perfectly inelastic collision is one in which the two objects do this

What is stick together?

500

The amount of force and object is subjected to if it experiences an impulse of 9.0 Ns for a total of 0.25 s. (F=I/t)

What is 36 N?

Miscellaneous 3: The Final Reckoning

100

This is not conserved in an inelastic collision

What is kinetic energy?

200

The final velocity of a 0.75 kg cart at rest that is struck by a 0.25 kg cart moving at 4.0 m/s before the collision and at -1.0 m/s after the collision [v_f2 = (m₁v_1i + m₂v_2i - m₁v_1f)/m₂]

What is 1.7 m/s?

300

The impulse on a 0.50 kg ball that was moving at 10.0 m/s, then struck a wall for 0.25 s and rebounded at 5.0 m/s in the opposite direction. (I = mv_f - mv_i)

What is 9.0 Ns?

400

This happens to the total kinetic energy in collision in which two objects stick together

What is it decreases?

500

The final speed of a 5 kg object that started out with 250 J of potential energy which were all converted into kinetic energy [v² = PE/2m]

What is 5 m/s?