Forces

Question 1

Newton’s first law

Answer 1

a resultant force is required to change the motion of an object

Question 2

Newton’s second law

Answer 2

if the resultant force is anything other than 0 then the object will accelerate

The size of the resultant force is directly proportional to the acceleration it causes i.e. if you make the resultant force twice as big, then the acceleration will also double

Question 3

When the resultant force is anything other than 0: a stationary object will

Answer 3

start moving

Question 4

When the resultant force is anything other than 0: if the object is already moving in the direction of the resultant force

Answer 4

accelerate

Question 5

When the resultant force is anything other than 0: if the object had been travelling in the opposite direction of the resultant force

Answer 5

decelerate

Question 6

If the speed or direction of an object change independently, this will cause acceleration because

Answer 6

acceleration = change in velocity/ change in time

so if velocity is made up of speed and direction, if any of the two change this contributes to acceleration

Question 7

Inertia

Answer 7

the tendency for the motion of an object to remain unchanged - how easy it is for a resultant force to change its motion - link to newton’s first law

Question 8

Intertial mass

Answer 8

how difficult it is to change an object’s velocity = force/acceleration so newton’s 2nd law rearranged

Question 9

Scalar

Answer 9

only magnitude e.g. distance/speed/time

Question 10

vectors

Answer 10

both magnitude and direction e.g. force/displacement/acceleration

Question 11

What is a free body diagram?

Answer 11

simple diagrams to show the forces acting on an object

magnitude + direction i.e. vectors (forces are represented using ‘force arrows’)

Question 12

velocity =

Answer 12

the speed of something in a given direction

Question 13

acceleration =

Answer 13

change in speed/change in time

Question 14

Terminal Velocity meaning/explained

Answer 14

Terminal velocity is the maximum speed attainable by an object as it falls through a fluid (air is the most common example)

As the velocity of the falling object increases, so does air resistance. Eventually, air resistance will equal the weight of the object in free fall. When this occurs, the object reaches terminal velocity. This means the falling object has reached its maximum velocity and acceleration is now zero.

Question 15

Terminal Velocity explained simply

Answer 15

Weight has the same magnitude as drag

Velocity = 0