Principles of force

Question 1

what is a force?

Answer 1

a push or a pulling action applied upon an object (measured in newtons, or N for short)

Question 2

what is the equation for force?

Answer 2

force=mass x acceleration

Question 3

what is inertia?

Answer 3

the resistance of an object to any change in its state of motion

Question 4

what are the effects of force?

Answer 4

• a force can cause an object/body at rest to move
• a force can cause a moving object or body to change direction
• a force can cause a moving object/body to accelerate
• a force can cause a moving object to decelerate
• a force can cause an object/body to change its shape

Question 5

what is mass?

Answer 5

the quantity of matter in a body regardless of its volume or of any forces acting on it (measured in kg)

Question 6

what is acceleration?

Answer 6

the rate at which an object changes speed (m/s2)

Question 7

what is gravity?

Answer 7

the force that attracts a body towards the centre of the earth, or towards any other physical body having mass

Question 8

what is muscular force?

Answer 8

a push or pull applied to an object provided by muscular contraction

Question 9

what is air resistance?

Answer 9

the frictional force that air applies against a moving object

Question 10

what is ground resistance force?

Answer 10

the reaction to the force that the body exerts on the ground

Question 11

why is ground resistance force important to sprinters?

Answer 11

in a sprint race, the starting blocks are in effect an angled extension of the ground. When a sprinter pushes against the blocks, the muscular force applied to them results in an equal reaction force from the blocks. This allows the sprinter to make an explosive horizontal burst

Question 12

what is a lever?

Answer 12

a solid bar (bone/s) that turns around an axis to create movement and contains 3 main components: fulcrum, resistance and effort

Question 13

what is fulcrum?

Answer 13

a fixed point about which the lever can turn; sometimes referred to as the axis or pivot

Question 14

what is resistance?

Answer 14

the load or weight that the lever must move (this could range from the weight of a body part to an external load such as dumb bells)

Question 15

what is effort?

Answer 15

the amount of force required to move the load

Question 16

what are first class levers?

Answer 16

a simple seesaw configuration: the fulcrum is in the middle and the resistance and effort are at either side of the fulcrum. Nodding the head is an example of a first-class lever in the body in action. 
Effort= force supplied by muscle contractions in the neck
Fulcrum= joint where skull meets the spine
Resistance= weight of head+ resistance from other muscles in the neck

Question 17

what are second-class levers?

Answer 17

the feature of the second-class lever is that the resistance is between the fulcrum and the effort. An example is lifting and moving a wheelbarrow, where the resistance is the load inside the barrow. The benefit of the second-class lever is that the effort used to move the load can be much less that that of the load itself. In the body, standing on your toes is an example. The foot being the bar at the centre of the lever system.
Effort= force supplied by muscle contractions in the gastrocnemius
Fulcrum= ball of the foot and joints of the toes
Resistance= the weight of the body going through the foot

Question 18

what are third-class levers?

Answer 18

third-class levers are common in the body and in sport. With a third-class lever the effort is placed between the fulcrum and the resistance. Doing a bicep curl is a good example of a third-class lever action.
Effort= force supplied by muscle contractions in the biceps; the bicep muscle inserts (is attached) about one inch below the elbow joint
Fulcrum= elbow joint
Resistance= the weight being lifted

Question 19

how are levers used to improve performance in sporting situations?

Answer 19

all movements that an athlete performs are produced by levers within the body. When a muscle pulls on a bone at a joint to create movement it uses the bone as a lever. These levers work together to apply forces that allow us to run, jump, throw, hit and kick