Question

A penny is submerged in a glass of water and held up horizontally by a string. The top of the penny experiences a pressure of 300 N/m² above atmospheric pressure. What pressure is incident on the bottom surface of the penny?

• A. just the pressure of the atmosphere
• B. about 150 N/m² above atmospheric pressure
• C. 0 N/m²
• D. about 300 N/m² above atmospheric pressure

The applied force to a hydraulic jack is 24 N to an area of 20 cm². What is the output force if the area on the other side is 10 m²?

A 3,000 kg treasure chest sits at the bottom of a lake. It is 1.5 cubic meters in volume. What buoyant force acts on it? (Density of water is 1,000 kg/m³)

A 100 N cube that is 1 meter on each side is put into a pond. How much of its volume will be underwater as it floats? (Use g = 10 m/s²)

Water is flowing continuously through a pipe that changes in diameter along its length. If the speed of flow is 0.2 m/s at a location where the cross sectional area is 10 cm², what is the speed where the cross sectional area is 15 cm²?

A strong wind blows over the flat rooftop of a building. As the wind speeds over the building....

• A. no force acts on the roof.
• B. a downward force acts on the roof.
• C. an upward force acts on the roof.

Check all that are true.

A. Measuring the temperature of a substance will tell you how much heat it contains.
B. Heat is energy that transfers between substances in contact when they have a temperature difference.
C. Heat is the amount of internal energy an substance has.
D. Heat transferred into a substance will raise its internal energy.

Answer 1

Multiple questions posted,so answering only the first question.

1) Gauge pressure in a static fluid is given by:P=dgh, where d is density of the fluid, g is gravitational acceleration and h is depth of the point where pressure is calculated.

The top and bottom surfaces of the penny are located at almost the same depth. So, h is same for both top and bottom surfaces. Also, d and g are the same for both the surfaces. Hence, gauge pressure at both the surfaces is same and is equal to 300 N/m2.

So,option D is correct.