Physics Pressure Quiz

A dam across a lake is divided into two sections by a rock. Section X is longer than section Y but the two sections are otherwise identical. The water in the lake by the dam is the same depth everywhere. The diagram shows a view from above of the lake and the dam. The water creates a total force on each section of the dam and an average pressure on each section of the dam. Which statement is correct?

• The average pressure on X equals the average pressure on Y.

• The average pressure on X is less than the average pressure on Y.

• The total force on X equals the total force on Y.

• The total force on X is less than the total force on Y.

A block with flat, rectangular sides rests on a table. The block is now turned so that it rests with its largest side on the table. How has this change affected the force and the pressure exerted by the block on the table?

• Force decreases and pressure decreased

• Force and pressure both are unchanged.

• Force decreases but pressure is unchanged.

• Force is unchanged but pressure decreases.

The diagram shows a stone suspended under the surface of a liquid from a string. The stone experiences a pressure caused by the liquid. What would increase the pressure on the stone?

• decreasing the surface area of the stone

• increasing the mass of the stone

• lowering the stone deeper into the liquid

• using a liquid with a lower density

The diagram shows a solid block resting on a bench. The dimensions of the block are shown. On which labelled surface should the block rest to produce the smallest pressure on the bench?

• P

• Q

• R

• any of P, Q or R

The table gives four forces and the surface area on which each force acts. Which row gives the largest pressure on the surface?

• A

• B

• C

• D

A man is in contact with the floor. In which of these situations does he produce the least pressure on the floor?

• kneeling

• lying flat on his back

• standing on both feet

• standing on one foot

A vehicle sinks into soft ground. The vehicle is changed so that it does not sink as far. Which change is made?

• A. a lower centre of mass

• B. a more powerful engine

• C. wheels that are further apart

• D. wider tyres

The pressure P1 at a certain depth in river water and P2 at the same depth in sea water are related

as:

• P1=P2

• P1 > P2

• P1 < P2

• Can not be decided

The diagram shows a dam holding back water.

The depth of the water is 65 m.

The density of the water is 1000 kg/m³. The gravitational field strength g is 10 N/kg.

What is the pressure exerted at the base of the dam due to the water?

• 15.4 Pa

• 154 Pa

• 65000 Pa

• 650000 Pa

• 6500 Pa

A drawing pin (soft-board pin) has a sharp point at one end and a flat surface at the other end.

The pin is pushed into a wooden board. How do the pressure and the force at the sharp point compare with the pressure and the force on the flat surface?

A

• A

• B

• C

• D