2. KINEMATICS

Question 1

distance def

Answer 1

total length of the path travelled by the body

Question 2

displacement def

Answer 2

distance travelled in a straight line in a specified direction from the initial position to the final position

Question 3

speed def

Answer 3

the rate of change of distance per unit time

Question 4

velocity def

Answer 4

the rate of change of displacement per unit time

Question 5

avg speed def

Answer 5

total distance travelled over the time taken

Question 6

avg velocity def

Answer 6

the change in displacement over the time taken

Question 7

acc def

Answer 7

rate of change of velocity with respect to time

Question 8

avg acc def

Answer 8

the change of velocity over the time taken

Question 9

path of projectile motion

Answer 9

parabolic

Question 10

conditions of projectile motion

Answer 10

1. object is not in contact with any other object
2. air resistance is negligible
   (the only force acting on the object is gf/W, acting vertically downwards)

Question 11

what is an object undergoing projectile motion characterised by?

Answer 11

1. constant velocity in the horizontal direction
2. constant acc in the vertical direction

Question 12

explain one-dimensional motion

Answer 12

• a body moving thru is subjected 2 forces, it’s weight and AR (always acts in the direction opposite to velocty/motion of the body)
• when the body first falls from rest, velocity is 0 and it doesn’t exp any AR
  –> the only force acting on the body is it’s weight
• as the body falls with increasing speed, AR acting upwards increases in magnitude
  –> net force on the body due to both W and AR and hence RF is less than W
  —–> by newton’s 2nd law, the body hence acc at a value smaller than g
• speed of body cont to increase as well as the AR acting on it
  –> eventually AR increases until it’s equal to W and hence net force acting on body decreases to 0
  —–> body falls with a constant maximum velocity, terminal velocity

Question 13

explain 2d motion

Answer 13

• as speed of the projectile changes, AR acts which acts in the direction opposite to the motion also changes
• as it travels up, both AR and WEIGHT act downwards and hence net downward force is larger
  –> by Newton’s 2nd law, the downward acc is therefore larger than g
  —–> which means the body will reach a smaller max height in a shorter period of time (Vy reduces to 0 in a shorter time)
• there is AR acting on the horizontal direction as well and hence horizontal velocity is reduced and horizontal range is smaller as well

–> the projectile trajectory is no longer symmetrical about its highest point