Forces pt2 (Pressure, upthrust, velocity, Newtons 1st law)

Question 1

what do pressure in fluids cause?

Answer 1

a force normal (at right angles) to any surface

Question 2

the equation for the pressure of fluids

Answer 2

pressure = force/area

Question 3

what does a liquid with high density mean?

Answer 3

means that it has more particles that are able you collide so the pressure is higher

Question 4

Why does liquid pressure increase with depth?

Answer 4

because the weight of all the particles above adds to the pressure felt at that point

Question 5

What does the pressure at a particular point in a column of liquid depend on?

Answer 5

• the height of the column above the point
• the density of liquid

Question 6

The higher the column and the denser the liquid………. (3)

Answer 6

• the greater the weight above the point
• the greater the force on the surface at that point
• the greater the pressure

Question 7

the for the pressure of fluids in a column

Answer 7

pressure = height of column x density of liquid x gravitational field strength

Question 8

How is atmospheric pressure created?

Answer 8

by air molecules colliding with the surface

Question 9

the greater the altitude…

(why is this)

Answer 9

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

Question 10

What is upthrust?

Answer 10

the upward force exerted by a fluid on a submerged object

Question 11

What happens when an object is submerged in liquid?

Answer 11

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.

Question 12

Why does an object float?

Answer 12

because the weight is equal to the upthrust

Question 13

Why does an object sink?

Answer 13

because the weight is greater than the upthrust

Question 14

What happens when an object is less dense than the liquid?

Answer 14

• 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

Question 15

what happens when the object is denser than the surrounding liquid?

Answer 15

it cannot displace enough liquid to equal its own weight so it sinks

Question 16

what is the size of upthrust equal to?

Answer 16

the weight of the liquid displaced

Question 17

When an object is travelling in circles…

Answer 17

-constantly changing direction = constantly changing velocity - accelerating even if travelling at a constant speed

Question 18

What is Newtons First law?

Answer 18

A body will remain at rest or a state of uniform motion in a straight line unless acted on by a resultant external force

Question 19

Newtons First law: The velocity of an object will only change…

Answer 19

if there is a resultant force acting on is

Question 20

Newtons First law: A non-zero resultant force will always produce…

Answer 20

acceleration or deceleration in the direction of the force

Question 21

what is inertia

Answer 21

the tendency of objects to continue in their state of rest or of uniform motion

Question 22

the equation for distance, speed and time

Answer 22

distance = speed x time