7.6 More calculations on motion along a straight line

Question 1

For motion along a straight line at constant acceleration, one direction along the line is _____ and the opposite direction is _____.

Answer 1

Positive

Negative

Question 2

What are the two stages of motion of an object being released from rest, falling and hitting a bed of sand

Answer 2

1 - Falling motion due to gravity, acceleration = g (downwards)
2 - Deceleration in the sand: initial velocity = velocity of object just before impact
The acceleration in each stage is NOT the same
The velocity at the end of the first stage is the same as the velocity at the start of the second stage

Question 3

Sign convention for forwards/up

Answer 3

+

Question 4

Sign convention for backwards/down

Answer 4

-

Question 5

For an object moving forwards and accelerating

Answer 5

v>0

a>0

Question 6

For an object moving forwards and decelerating

Answer 6

v>0

a<0

Question 7

For an object moving backwards and accelerating

Answer 7

v<0

a<0

Question 8

For an object moving backwards and decelerating

Answer 8

v<0

a>0

Question 9

Value of g

Answer 9

9.8ms^-2