Motion

Question 1

What does a distance time graph give?

Answer 1

• Shows speed given by gradient
• Cannot be negative
• A negative gradient means the object is moving towards the start

Question 2

What does a speed time graph give?

Answer 2

• Acceleration given by gradient
  -Area under graph gives distance
• Positive gradient means object is speeding up

Question 4

What is the relationship between the vertical and horizontal motion of a projectile?

Answer 4

-They are independent from each other.

Question 5

What is the acceleration of the vertical and horizontal components of a falling object?

Answer 5

-Vertical - experiences a constant acceleration of g in the vertical plane (due to the weight of an object)
-Horizontal - 0 acceleration as acceleration is only in the vertical component and gravity has no effect on the horizontal component.

Question 6

When a projectile is flying, what are the only forces acting on it?

Answer 6

-The weight of the object which acts vertically down
-Drag (if mentioned in the question)
-There are NO HORIZONTAL FORCES

Question 7

How does the vertical velocity of a projectile change?

Answer 7

-First decreases until it reaches 0 at maximum height -Changes direction after reaching maximum height and begins to increase until hitting the floor

Question 8

For a moving projectile travelling in a negatively parabolic line,why would the GPE gained from the start to the max height not be the same as its initial KE?

Answer 8

The ball still has horizontal motion despite vertical motion being 0.

Question 9

How do you calculate the magnitude of speed? When would you use the magnitude of speed?

Answer 9

• sqr(a^2 +b^2) = c
  -When the question only asks for SPEED and does not specify vertical or horizontal velocity

Question 10

How would you use a tennis ball and a stopwatch to calculate the acceleration of free fall?

Answer 10

-Drop a ball from rest from a given height and measure time of fall
-Use formula s= ut+1/2at^2
-Rearrange formula to
a= 2s/t^2