linear motion Flashcards
forces acting on during LM, D+E+U scalars and vectors ,
what is linear motion
Is the movement in a straight line or curve with all body parts moving the same distance at the same speed in the same direction
do projectiles show linear motion
yes
what is parabolic flight
a curve of a projectile
what is a vector
vectors are forces that have both a magnitude (size) and direction
what are scalar quantities
are when measurements are only described as a magnitude only
is mass a scalar or vector
scalar
what is an Internal force plus eg
An internal force is applied when our skeletal muscles contract
eg the force produced by the quadriceps when we jump
what is an External force plus egs
An external force comes from outside the body
for example friction, air resistance and weight (gravity)
identify and explain two external forces acting on the athlete in the photograph (an athlete performing a long jump) the jumping bit (4)
air resistance (1) this will be acting in the opposite direction of travel to the jumper/will depend on the velocity of the jumper/cross sectional area/the streamlining/shape of the jumper (1)
weight/gravity (1) this will be pulling the jumper downwards towards the sand pit/greater the mass of jumper=greater the weight force pulling them down
what are the vertical forces
weight, reaction force.
identify one vertical force and one horizontal force acting on a performer when running in a 100m sprint
vertical: weight/(ground) reaction force/gravity
horizontal: friction/air resistance
what is reaction force
whenever forces act on a performer there will always be a reaction force
is friction a vertical or horizontal force
horizontal
friction occurs when
friction occurs when 2 or more bodies are in contact with one another
what are the 2 types of friction
sliding and static friction
what is static friction
Is the force exerted on one surface by another when there is no motion between the surfaces
apply static friction to a netballer
a netballer stationary prior to them using the floor to generate movement
what is Sliding friction def and exp
Sliding friction acts between two surfaces that are moving relative to one another.
a runner exerts and action force (internal) downwards and backwards in order to move forwards, and so friction acts opposite to this force (forwards), it acts in the same direction as motion (in this case)
apply sliding friction to a skier
the slippage is downhill and they are applying force forwards in order to go forwards as there is the additional gravity of going down a hill, and so friction acts opposite to that forward force and so friction acts backwards
what are the 3 factors that affect friction
surface characteristics
temperature
mass of object
how does surface characteristics affect friction inc eg
running spikes will increase friction of the runner and so will increase accel
ice is smooth and so has/could have “zero friction”
how does temperature influence friction inc eg
as temperature increases the amount of friction is reduced eg sweeping the ice in curling
how does mass affect friction
as the mass of the object increases, friction increases
what is air resistance
A force that acts in the opposite direction to the motion of a body travelling through the air
is air res a horizontal or vertical force
horizontal
what are the factors affecting air resistance
velocity of the moving object
mass
front cross sectional area
shape of the surface
how does velocity affect air resistance
more velocity=more air resistance
how does mass affect air resistance
less mass=more air resistance