The two nuclei that can sustain a nuclear chain-reaction are ...

[fbq8i]

The two nuclei that can sustain a nuclear chain-reaction are
 
  A) thorium and plutonium.
  B) 238U and plutonium.
  C) thorium and 235U.
  D) 235U and plutonium.
  E) Actually, there is only one nucleus that can sustain a nuclear chain-reaction.

Question 2

Can an object have mechanical energy without having momentum? Can an object have momentum without having mechanical energy? Explain.
 
  What will be an ideal response?

Question 3

Give two explanations of why a cannonball fired from a long-barrel cannon will have a greater velocity than from a shorter cannon.
 
  What will be an ideal response?

[rnehls]

Answer to Question 1

D

Answer to Question 2

wohoo thank youuu.

Answer to Question 3

Answer: In terms of impulse-momentum, the longer barrel means the time during which the exploding powder pushes on the cannonball is longer. This means more impulse, which in turn means more gain in momentum, and greater velocity. In terms of work-energy, the longer barrel means a longer distance for the force to act, which means greater work on the ball inside the barrel and more gain in kinetic energy, and greater velocity.

[fbq8i]

Excellent

[cpetit11]

Gracias!