Energy transformation

Two students place three ice cubes in a glass of water that was at room temperature. Which of the following scenarios would best describe the results of the investigation?

• Energy from the water will transfer to the ice cubes, causing the ice to melt.

• Cold from the ice cubes will transfer to the water, causing the water to cool.

Where would an object have the most potential energy?

• The bottom of a hill

• The top of the hill

• On the way down the hill

• It never has potential energy

How does a windmill change forms of energy?

• Mechanical to electrical

• Electrical to mechanical

• Mechanical to light

• It is unable to change forms

Which statement correctly compares the difference between conduction and convection in a classroom?

• Conduction can only occur in solids, while convection

  can occur in both liquids and gases.

• Convection can only occur in solids, while conduction

  can occur in both liquids and gases.

• Conduction can only occur in liquids and gases, while

  convection can occur in solids, liquids, and gases.

• Convection can only occur in liquids and gases, while

  conduction can occur in solids, liquids, and gases.

Which of the following gadgets best shows the transformation of energy from electrical to mechanical with the correct reasoning?

• A light bulb because electricity is being used to create light and heat.

• A fan because electricity is being used to spin the blades of the fan.

1. A hot (100 °C) bolt with a mass of 71 grams is placed in 150 grams of cool (20 °C) water.

This diagram shows the resulting temperature changes. The specific heat of water is 4.184 J/g × °C.

Approximately how many joules of heat did the water absorb?

(Heat Lost or Gained = Mass × Specific Heat × Change in Temperature) (Q = m c ΔT)

• 2,510.40 J

• 1,118.26 J

• 1,506.24 J

• 22,191.94 J

If 200 J of energy were added to 1 g each of aluminum and copper, which would experience the LEAST temperature increase. Refer to the formula below:

 $Q\ =\ mc\Delta T\ \ \ \ \ \ c\ =\ specific\ heat\ capacity$  

• Aluminum (c = 0.9 J/g C), because the higher the value for specific heat, the more energy is required for temperature change.

• Copper (c = 0.39 J/g C), because the lower the value for specific heat, the more energy is required for temperature change.

During a lab investigation, energy was removed from two different materials.
Material A had a temperature change of  $7\degree C$  

Material B had a temperature change of  $42\degree C$  
Which conclusion about the specific heat of the materials is best supported by this information?

• Material A has a lower specific heat value than B because it had the least change in temperature.

• Material B has a lower specific heat value than material A because it showed the greatest change in temperature.

A girl is riding her bike at a speed of 12 m/s. The girl and her bike have a combined mass of 77 kg. What is the KE of the girl and her bike? Use the formula:  

 $KE\ =\ \frac{1}{2}\ mv^2$  

• 1078 J

• 5544 J

A student decides to take up diving as a hobby. He stands on a high-dive that is 4m tall. If the student has a mass of 50 kg, what is his PE? Use the following equation to solve:

 $PE\ =\ mgh$  g = 9.8 m/s/s

• 1960 J

• 200 J