Principles of force Flashcards
what is a force?
a push or a pulling action applied upon an object (measured in newtons, or N for short)
what is the equation for force?
force=mass x acceleration
what is inertia?
the resistance of an object to any change in its state of motion
what are the effects of force?
- 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
what is mass?
the quantity of matter in a body regardless of its volume or of any forces acting on it (measured in kg)
what is acceleration?
the rate at which an object changes speed (m/s2)
what is gravity?
the force that attracts a body towards the centre of the earth, or towards any other physical body having mass
what is muscular force?
a push or pull applied to an object provided by muscular contraction
what is air resistance?
the frictional force that air applies against a moving object
what is ground resistance force?
the reaction to the force that the body exerts on the ground
why is ground resistance force important to sprinters?
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
what is a lever?
a solid bar (bone/s) that turns around an axis to create movement and contains 3 main components: fulcrum, resistance and effort
what is fulcrum?
a fixed point about which the lever can turn; sometimes referred to as the axis or pivot
what is resistance?
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)
what is effort?
the amount of force required to move the load
what are first class levers?
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
what are second-class levers?
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
what are third-class levers?
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
how are levers used to improve performance in sporting situations?
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
