physics Flashcards
What is a force?
A push or a pull
What units are used to measure force?
Newtons (N)
What is force measured by?
Newton Balance
What direction will an object move when a force is unbalanced?
It will move in the direction of the larger force
The larger the unbalanced force…
the greater the acceleration
To find total force acting on an object
forces acting in the same direction can be added together and forces acting in opposite directions can be subtracted
what is friction?
friction is when two surfaces rub together
What does friction always do?
opposes motion and slows things down
What increases friction?
rough surfaces or surfaces with large surface area
What increases grip?
Increasing friction
What is water resistance?
When water rubs on a body
What is streamlining?
Streamlining is when we change the shape of an object to decrease air or water resistance.
What is air resistance?
When air rubs on a body
What also reduces friction?
lubrication
What are streamlined objects usually like?
Streamlined objects are smooth and curved are smooth and curved and usually close to the ground.
What do cyclists do to reduce friction?
They wear skin tight clothing, wear streamlined helmets and bend over their handlebars to reduce friction
What do swimmers do to reduce friction?
They wear skin tight clothing, shave hair from their arms and legs and wear swimming caps
What do FINA state that swimmers must do when swimming?
They state that swimmers must break the surface before 15m, because swimming underwater is easier and faster, using less energy
What is newton’s third law of motion?
Newton’s third law of motion states that for every acting force, there is an equal and opposite reaction force.
Give an example of Newton’s third law
In swimming, we push water backwards, and the water pushes us forward.
What are the four main types/strokes of swimming?
Freestyle, breaststroke, backstroke and butterfly
how do parachutes work?
Parachutes have a large surface area, they increase air resistance and slow things down.
What is an object called when it is kicked or thrown?
a projectile.
What is the name of the curved path a projectile follows?
a trajectory.
Do all objects fall to earth at the same rate?
yes, regardless of their mass due to the pull of gravity.
What is vertical motion caused by?
It is caused by gravity.
When does vertical motion increase?
When gravity is present.
When does horizontal motion decrease?
When air resistance is present.
What is the range of a projectile?
It is the horizontal distance.
What is horizontal distance affected by?
the force of the kick and the angle.
How do you measure speed in m/s?
measure the distance travelled in one second.
How to you calculate the speed in m/s
Calculate distance divided by time.
What units are used in a distance/time calculation?
meters/second (m/s)
What is reaction time?
Reaction time is the time between a stimulus (something happening) and a muscular response (the body doing something).
When we see a stimulus, how does this lead to our muscles moving?
We see the stimulus with our eyes. The eyes send a message to the visual cortex in the brain. The brain then sends a message to our motor cortex. The motor cortex sends a message to the spinal cord, which sends a message to make the muscles move.
Give an example of when reaction time is important.
in sports (like racing) reaction time is important because of the small margins between winning and losing.
