The correct answer should be D. copper
Nickel, cobalt, and iron, produce magnetic fields when electrified while copper does not.
Answer:
1) Unbalanced
2) Balance
3) Balanced
4) Unbalanced
5) Unbalanced
Explanation:
For 1 and 5, since the objects are not at a constant speed/velocity, their forces must be unbalanced.
For 2 and 3, their speeds are constant so that means the force is balanced. If the bycicle or box started accelerating, that would indicate an unbalanced force
For 4, the speed is constant, but it's direction is not indicating another unbalanced outside force causing it to turn. The force is unbalanced.
Well, when you want to accomplish a goal, you can't take forever to do it now can you? No. The purpose of setting a deadline for your goal is for motivation. You become motivated to do it, instead of putting it off for later. You want to get it done in a reasonable amount of time.
Answer:
The friend is wrong: the law of conservation of momentum is not violated
Explanation:
The law of conservation of momentum states that:
"For a system of an object, if the net external force acting on the system is zero, then the total momentum of the system is conserved"
In our problem, the system is the ball rolling down the hill. The ball gains speed as it rolls down, so its momentum increases, according to the equation:

where m is the mass of the ball and v its velocity. This may appear as a violation of the law, however it is not. In fact, the net external force acting on the ball is not zero, since there is the force of gravity acting on the ball. As a result, the force of gravity gives an acceleration to the ball, increasing its momentum: therefore, the law is not violated.