Quiz 1

Which of the following properties must be known in order to calculate the amount of heat needed to melt 1.0 kg of ice at 0ºC?

I. The specific heat of water

II. The latent heat of fusion for water

III. The density of water

• I only

• I and II only

• I, II, and III

• II only

Which of the following is an example of convection?

• The heat of the sun warming our planet

• The heat from an electric stove warming a frying pan

• A microwave oven cooking a meal

• An overhead fan cooling a room

A heat engine produces 100 J of heat, does 30 J of work, and emits 70 J into a cold reservoir.

What is the efficiency of the heat engine?

• 100%

• 70%

• 40%

• 30%

A person sips a drink through a straw. At which of the following three positions is the pressure lowest?

I. Inside the person’s mouth

II. At the surface of the drink

III. At the bottom of the drink

• only at position I

• only at position II

• only at position III

• both at positions I and II

Brian saves 2-liter soda per bottles so that he can construct a raft and float. If Brian has a mass of 80 kg, what minimum number of bottles is necessary to support him? The density of water is 1000 kg/m^3, and 1000 L = 1 m^3.

• 1600 bottles

• 800 bottles

• 40 bottles

• 4 bottles

A pirate ship hides out in a small inshore lake. It carries twenty ill-gotten treasure chests in its hold. But lo, on the horizon the lookout spies a gunboat. To get away, the pirate captain orders the heavy treasure chests jettisoned. The chests sink to the lake bottom. What happens to the water level of the lake?

• The water level drops.

• The water level rises.

• The water level does not change.

• The water level equal to the wight of the ship

A copper wire of diameter d is stretched by a load hanging vertically from its lower end. The strain of the wire is 8.0x10^-4. What is the strain in another copper wire of the same lenght but of diameter 2d?

• 2.0 x 10^-4

• 4.0 x 10^-4

• 1.6 x 10^-4

• 3.2 x 10^-4

In an experiment to measure the young's modulus of steel, a student uses a steel wire.

Length of wire = (3.00± 0.01) m

Diameter of wire = (0.55 ± 0.01) mm

Mass of load = (8.00 ± 0.01) kg

Extension = (3.00 ± 0.01) mm

• Measurement of length

• Measurement of diameter

• Measurement of mass

• Measurement of extension

A steel wire and a copper wire of equal length and diameter are joined at one end. A longitudinal force F is applied to the free ends.

If the young's modulus of steel is twice that of copper, which statement is true?

• The extension of the copper wire is twice of the steel wire.

• The stress of the steel wire is twice of the copper wire.

• The strain of the steel wire is twice of the copper wire

• The final length of the copper wire is twice of the steel wire.

A copper rod of cross sectional area 0.5cm^2 and length 1.0m is elongated by 2.0x10^-2 mm, and a steel rod of the same cross sectional area but 0.1m in length is elongated by 2.0x10^-3mm. Which rod has greater tensile strain?

• The copper rod

• The steel rod

• The starin is the same for both

• the aluminum rod