pe biology chapter 5

Question 1

newtons first law is the …

this states:

Answer 1

law of inertia

inertia is the resistance an object has to change in the state of motion

Question 2

newtons second law is the …

it states:

Answer 2

law of acceleration
the greater the force applied the greater the acceleration (rate of change of momentum). this is because acceleration is proportional to the size of the force

Question 3

newtons third law is the …

it states:

Answer 3

law of action/reaction

apply a force and there is equal and opposite reaction

Question 4

give a sporting example for newtons first law:

Answer 4

the football will continue to travel in the same direction until the goalkeeper applies an external force onto the football

Question 5

give a sporting example for newtons second law:

Answer 5

the harder the ball is kicked, the further and faster it will go in the direction in which the force was applied

Question 6

give a sporting example for newtons third law:

Answer 6

when a basketballer jumps up to block or shoot, a force is exerted on the ground in order to gain height at the same time the ground exerts an upwards force, equal and opposite reaction

Question 7

what is linear motion

Answer 7

motion in a straight or curved, with all body parts moving in the same direction

Question 8

SCALAR quantities speed and distance formula:

Answer 8

speed in metres per second (ms) = distance covered in metres (m) / time taken in seconds (s)

Question 9

position of the centre of mass

Answer 9

point of balance

Question 10

line of gravity

Answer 10

line extending vertically downwards from the centre of mass

Question 11

base of support

Answer 11

larger the area, greater the stability

Question 12

how a lever works in our body:

Answer 12

• joints of our skeleton not only allow movement, they also act as levers
• joints itself is the fulcrum (pivot)
• “effort” is provided by the contracting muscle
• “load” comes from the body part being moved

Question 13

what are levers two functions:

Answer 13

to apply force (strength) to an object
* the longer the lever distance from the fulcrum, the greater the force generated

to move the load a greater distance or through a greater range of movement
* the closer the effort is to the fulcrum, the grater the distance moved

Question 14

first class levers: Lots of Fun Everywhere

Answer 14

seesaw
load fulcrum effort
e.g. dumbbell tricep extensions and tricep dips
e.g. neck (nodding)

Question 15

second class levers: Floor Loads of Enemies

Answer 15

rare in the body
fulcrum load effort
e.g. exercises that require extending the ankle, such as seated or standing calf-raises

Question 16

third class levers: Lies in Every Form

Answer 16

most common form of lever in the human body
load effort fulcrum
in terms of applying force this is a very inefficient lever, BUT IT ALLOWS SPEED AND RANGE OF MOVEMENT
e.g. knee (flexion and extension)
elbow (flexion)

Question 17

two benefits of levers:

Answer 17

• large loads can be moved with a relatively small amount of effort
• the distance a load can be moved, or the speed with which it can be moved, can be increased without an increase in effort

Question 18

what is the load arm:

Answer 18

distance from the load to the fulcrum

Question 19

what is the effort arm:

Answer 19

distance from the effort to the fulcrum

Question 20

when a levers effort arm is longer than its load arm it is said to have a:

Answer 20

mechanical advantage:

• can move large loads with less effort
• SECOND CLASS LEVERS ALWAYS HAVE A MECHANICAL ADVANTAGE

Question 21

when a levers load arm is longer than its effort arm it is a:

Answer 21

mechanical disadvantage:

• whilst called a disadvantage, third class levers are able to increase the speed at the end of the lever arm
• THIRD CLASS LEVERS ALWAYS HAVE A MECHANICAL DISADVANTAGE

Question 22

a summary of effects and benefits of levers:

Answer 22

• first class - can increase both effort and the speed of a body
• second class - tend only to increase the effect of the effort force
  third class - can be used to increase the speed of a body