P9- Motion

Question 1

What is velocity?

Answer 1

Velocity is a vector quantity (it is speed in a given direction)

Question 2

Why does a car travelling around a round-a-bout have a constant speed but a changing velocity?

Answer 2

the direction of motion is changing continuously so its velocity is not constant even if its speed is constant

Question 3

What is the difference between displacement and distance?

Answer 3

displacement is the distance travelled in one direction (it is a vector quantity) from one point to another whereas distance describes the route and can act in various directions

Question 4

What is acceleration?

Answer 4

The acceleration of an object is its change in velocity per second

Question 5

What are the units for acceleration?

Answer 5

m/s^2

Question 6

How do you calculate acceleration?

Answer 6

acceleration= change in velocity/ time taken
a= change in v/ t

Question 7

How do you calculate resultant force?

Answer 7

resultant force= mass x acceleration

Question 8

What is the method for investigating acceleration when mass is constant?

Answer 8

1)Position an air track on a bench with a bench pulley at one end and two light gates above the track.

2)Cut an interrupt card to a known length (such as 10 cm) and attach it to a trolley

3)Connect the trolley to a mass hanger by a string the length of the air track passing over the bench pulley.

4)Set the data logging software to calculate acceleration.

5)Start off with an 100g mass and release the trolley

6) Record the force applied to the string using the equation (weight= mass x gravitational field strength) and the acceleration in a table

7) Repeat the experiment several times for each mass ensuring you are recording it in the table, then remove mass from the hanger, 10g at a time.

8)Complete the experiment again. Ensure that the masses that are taken off of the mass hanger are placed on the trolley to keep mass in the system constant

9) plot a graph of force against acceleration, force on the x axis and acceleration on the y axis

Question 9

How do you calculate acceleration from a velocity time graph?

Answer 9

the acceleration is the gradient

Question 10

How do you calculate displacement on a velocity time graph?

Answer 10

The displacement is the area underneath the graph

Question 11

On a velocity time graph, what does the horizontal line show?

Answer 11

It shows a constant velocity meaning that the acceleration is 0

Question 12

How do you calculate the gradient of a line?

Answer 12

m= change in y/ change in x