Forces pt2 (Pressure, upthrust, velocity, Newtons 1st law) Flashcards
what do pressure in fluids cause?
a force normal (at right angles) to any surface
the equation for the pressure of fluids
pressure = force/area
what does a liquid with high density mean?
means that it has more particles that are able you collide so the pressure is higher
Why does liquid pressure increase with depth?
because the weight of all the particles above adds to the pressure felt at that point
What does the pressure at a particular point in a column of liquid depend on?
- the height of the column above the point
- the density of liquid
The higher the column and the denser the liquid………. (3)
- the greater the weight above the point
- the greater the force on the surface at that point
- the greater the pressure
the for the pressure of fluids in a column
pressure = height of column x density of liquid x gravitational field strength
How is atmospheric pressure created?
by air molecules colliding with the surface
the greater the altitude…
(why is this)
the less dense the atmosphere and the lower the atmospheric pressure
- this is because there are fewer air molecules that are able to collide with the surface
What is upthrust?
the upward force exerted by a fluid on a submerged object
What happens when an object is submerged in liquid?
The pressure of the fluid exerts a force from every direction the bottom surface experiences a greater pressure than the top surface and this creates a resultant force upwards.
Why does an object float?
because the weight is equal to the upthrust
Why does an object sink?
because the weight is greater than the upthrust
What happens when an object is less dense than the liquid?
- it will displace a volume of liquid greater than its own weight so it will rise to the surface
- will float with some of the object remaining below the surface
- displaces liquid of equal weight to the object
what happens when the object is denser than the surrounding liquid?
it cannot displace enough liquid to equal its own weight so it sinks
what is the size of upthrust equal to?
the weight of the liquid displaced
When an object is travelling in circles…
-constantly changing direction = constantly changing velocity - accelerating even if travelling at a constant speed
What is Newtons First law?
An object will remain in the same state of motion unless acted on by an external force
Newtons First law: The velocity of an object will only change…
if there is a resultant force acting on is
Newtons First law: A non-zero resultant force will always produce…
acceleration or deceleration in the direction of the force
what is inertia
the tendency of objects to continue in their state of rest or of uniform motion
What is the speed of walking?
1.5 m/s
What is the speed of running?
3m/s
What is the speed of cycling?
6 m/s
What is the speed of sound?
330 m/s
the equation for distance, speed and time
distance = speed x time
