ACT Science Review

Which of the following graphs best illustrates the relationship between the heat released by the foods listed in Table 1 and the change in water temperature?

• A
• B
• C
• D

According to Tables 1 and 2, as the mass of successive sucrose samples increased, the change in the water temperature produced when the sample was burned most likely:

• Increased only
• Decreased only
• Increased, then decreased
• Stays the same

Which of the following lists the foods from Tables 1 and 2 in increasing order of the amount of heat released per gram of food?

• Potato, egg, bread, sucrose, cheese
• Sucrose, cheese, bread, egg, potato
• Bread, cheese, egg, potato, sucrose
• Sucrose, potato, egg, bread, cheese

Based on the information in Tables 1 and 2, the heat released from the burning of 5.0 g of potato in a bomb calorimeter would be closest to which of the following?

• 5 kJ
• 10 kJ
• 15 kJ
• 20 kJ

In Experiment 1, the time constant of the circuit was the time required for the voltage across the capacitor to reach approximately 7.6 V. The time constant of the circuit used in Experiment 1 was:

• Less than 12 sec
• Between 12 sec and 24 sec
• Between 24 sec and 36 sec
• Greater than 36 sec

If, in Experiment 2, a 1.5 × 10–6 F capacitor had been used, the time required for the voltage across the capacitor to reach 6 V would have been closest to:

• 4.2 sec
• 7.0 sec
• 10.5 sec
• 15.0 sec

The main purpose of Experiment 3 was to determine how varying the:

• battery’s voltage affected the resistor’s resistance at a given time.
• capacitor’s capacitance affected the time required for the voltage across the capacitor to reach a set value.
• . capacitor’s capacitance affected the voltage across the battery at a given time.
• resistor’s resistance affected the time required for the voltage across the capacitor to reach a set value.

Consider a circuit like that shown in Figure 1. Based on Experiments 2 and 3, the voltage across the capacitor will reach a given value in the shortest amount of time if the circuit contains which of the following capacitances and resistances, respectively

• 0.1 × 10–6 F, 0.3 × 107 Ω
• 0.1 × 10–6 F, 1.0 × 107 Ω
• 1.2 × 10–6 F, 0.3 × 107 Ω
• 1.2 × 10–6 F, 1.0 × 107 Ω

Consider the following hypothesis: In a circuit arranged as in Figure 1 containing a battery, a capacitor, and a constant resistance, as capacitance increases, the time required to reach a given voltage across the capacitor increases. Do the experiments support this hypothesis?

• Yes; in Experiment 1, as capacitance increased, the time required to reach a given voltage increased.
• Yes; in Experiment 2, as capacitance increased, the time required to reach a given voltage increased.
• . No; in Experiment 1, as capacitance increased, the time required to reach a given voltage decreased.
• . No; in Experiment 2, as capacitance increased, the time required to reach a given voltage decreased.

A student wants to test the effects of type of exercise on heart rate.  What is the independent variable?

• type of exercise
• heart rate
• amount of time exercise occurs
• gender of person that exercises