Everything Science Grade 12

6.5 CHAPTER 6. MOTIONIN TWO DIMENSIONS

Questions:

1. What are isotopes? (2)


2. What are atoms made up of? (3)


3. Why do you think protons are used in theexperiments and not
   atoms like carbon? (2)


4. Why do you think itis necessary to find outwhat atoms are made
   up of and how they behave during collisions? (2)


5. Two protons (mass 1 , 67 × 10 −^27 kg) collide and somehow stick
   together after the collision. If each proton travelled with an initial
   velocity of 5 , 00 × 107 m· s−^1 and they collided at an angle of 90◦,
   what is the velocity of the combination after thecollision. (9)

6.5 Frames of Reference

ESCDF

Introduction ESCDG

N

S

W E

�

�

A

B

A’s left A’s right

B’s right B’s left

Figure 6.8: Top view ofa road with two people standing on opposite sides. A car drives

past.

Consider two people standing, facing each other on either side of a road. A car drives

past them, heading West. For the person facingSouth, the car was moving toward the

right. However, for theperson facing North, thecar was moving towardthe left. This

discrepancy is due to thefact that the two peopleused two different frames of reference

from which to investigate this system. If each person were asked in what direction the

car were moving, they would give a different answer. The answer wouldbe relative to

their frame of reference.