SP9g Pressure and Upthrust

Question 1

What will an object feel if you immerse it in a fluid?

Answer 1

.pressure of the atmosphere pushing down on the surface of the liquid
.additional weight of the column of liquid above it

Question 2

force (weight of column of fluid) = ?

Answer 2

mass x gravitational field strength

Question 3

pressure due to column of liquid (Pa) = ?

Answer 3

height of column (m) x density of fluid (kg/m³) x gravitational field strength (N/kg)

Question 4

Upthrust?

Answer 4

upward force (an object partly or completely submerged in a fluid has this upward force acting on it)

Question 5

Why does upthrust occur?

Answer 5

due to the difference in pressure on the bottom of a surface compared to the top of a surface.

Question 6

What is upthrust equal to?

Answer 6

the weight of fluid displaced by an object.

Question 7

If an object is less dense than fluid it will float, why?

Answer 7

because weight of water displaced by the object is greater than the weight of the object itself.

Question 8

If an object is denser than fluid it will sink, why?

Answer 8

because weight of water displaced by the object is less than the weight of the object itself.

Question 9

Explain 4 factors that determine whether an object will float or sink.

Answer 9

.density - if an object is lighter than the fluid it will float, if not it will sink
.buyant force - if fluid pushes up on an object with a force greater than its weight it floats, otherwise it sinks
.volume - bigger objects are more likely to float because they displace more fluid
.shape and surface area - objects with larger surface areas or shapes that trap air are more likely to float