Vectors: magnitude cannot be negative; sign (+/–) is the direction.

Chapter 2, Problems 1-19

  1. Which force, electromagnetic(E), gravitational(G), weak nuclear(WN) or strong nuclear(SN), is primarily responsible for the following:
charging a battery. __E__ hitting a baseball. ___ E__
shaking of a earthquake. ___E__ skating on a frozen lake. __ E__ and __G__
twinkling of star. ___ E__ coloring of paints. __ E___
cauterizing an injury. ___ E__ decay of dead plants. __ E___
dying of cloth. __ E___ singing a song. __ E___
tanning of leather. ___ E beating of the heart. __ E___

 

2. An ideal spring will have the natural length if there are no forces acting on it.

3. A massless ideal spring will not remain stationary if a force is applied to only one end.

4. The force vectors = +X , and = –X, can stretch a stationary spring.

5. The angle between the force vectors = –F , and = +F , is 180°.

6. There is not a value for C , making vectors, , and , equal:

C = there is none. The reason is vectors must point in the same direction to be equal.

7. The sum of 5 vectors is a vector

8. Given that F = –F , and T = +T , where F = 2T , the value of S = F+T = –T.

9. A kid's toy that is definitely not an ideal spring is a slinky.

10. Tension forces are generated in a material in response to stretching.

11. Compression forces are generated in a material in response to squeezing.

12. A drawing of a stretched spring showing only the spring and the force vectors acting on it , F , and generated by it , T , (the T forces act on the objects generating the forces F) is shown below

13. Two force vectors that have equal magnitudes and opposite directions will cause tension or compression forces in the object they act on.

14. Two forces with equal magnitudes and opposite directions acting on a single object will balance. On two unconnected objects they will not balance.

15. Newton's third law is: For every action there is an equal and opposite reaction .

16. The forces in Newton's third law act between (#) two objects, one on each object.

17. The magnitude of the tension forces acting in the rope on either side of a massless, and frictionless, pulley are always equal to each other. The pulley will turn to make this true.

18. Two force vectors can not "balance" and be "equal" at once. Reason: balanced forces must have opposite directions while equal forces must have the same direction.

19. A stationary spring that is stretched by an amount, x , by a force applied to both ends will stretch a distance 2x if the force is doubled on both sides of the spring.

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