Science Midterm answers Lesson 3

In your own words, explain viscosity,

cohesion and adhesion.

Another way to think of viscosity is the ‘thickness’ of

the fluid or the ability of the fluid to flow.

Cohesion is the force of attraction between the

particles of the same substance

Adhesion is the force of attraction between the

particles of one substance and the particles of

another substance

Calculate the flow rate in the following

situations.

a.The average shower is 8 minutes long

and uses 62 L of water.

b. The average bath takes 5 minutes to fill

and uses 80 L of water.

Flow rate = volume/length of time

= 62L/8min

= 7.75L/min

Flow rate = volume/length of time

= 80L/5min

= 16L/min

Calculate how much water is used in each

situation.

a. Your tap flows at 2L/min and you leave it running for the 2.5 minutes it takes you to brush your teeth.

b. Your garden hose flows at 140L/min and it takes you 1.5 hours to water your lawn.

Volume = Flow rate x length of time

V = 2L/min x 2.5 min

V = 5L

Volume = Flow rate x length of time

V = 140L/min x 90 min = 1.5 hours

V = 12600L

1.5 hours x 60 mins = 90 mins

Choose three common fluids and list them in order of viscosity, cohesion and adhesion.

Oil, water, alcohol

Viscosity: 1. Oil 2. Water 3. Alcohol

Cohesion: 1. Water 2. Alcohol 3. Oil

Adhesion: 1. Oil 2. Water 3. Alcohol

Why do fluids travel faster in the centre of pipes and streams than at the edges?

Adhesion causes fluids to flow faster in the middle of pipes rather than at the edges because the fluids stick to the pipes as they pass. Fluids also flow faster in the center of a stream than at the edges because the fluids stick (adhesion) to the sides (banks) and bottom of the stream.

Complete the following statements using the words ‘increases’ or ‘decreases’.

a. As viscosity increases, the flow rate decreases.

b. As cohesion increases, the flow rate decreases.

c. As adhesion increases, the flow rate decreases.