P.O.E. Unit 1 Test

Uranium is not a fossil fuel because it is not derived from the remains of ancient plants and animals. It is a radioactive metal that is found in the Earth's crust and is used as a fuel in nuclear power plants to produce electricity. Fossil fuels, on the other hand, such as natural gas, oil, and coal, are formed from the remains of plants and animals that lived millions of years ago and have undergone chemical and geological processes over time.

Wind is the correct answer because it is an inexhaustible energy source. Unlike coal, biomass, and uranium, which are finite resources that will eventually run out, wind energy is renewable and will never be depleted. Wind power harnesses the natural movement of air to generate electricity, and as long as wind exists, this energy source can be continuously utilized without causing harm to the environment or depleting its supply.

Power is defined as the rate at which work is done or energy is transferred. It is calculated by dividing the amount of work done by the time it takes to do it. In this case, the horse performs 12000 joules of work in 27 seconds. To find the power, we divide 12000 joules by 27 seconds, which gives us approximately 444.44 watts.

Gear B changes the direction of Gear C. This means that when Gear B rotates in one direction, Gear C will rotate in the opposite direction. This is a common function of gears in a system, where one gear is used to reverse the direction of rotation of another gear.

When the resistance in a series circuit is increased while keeping the voltage the same, the current will decrease. This is because according to Ohm's Law (V = IR), as resistance increases, the current flowing through the circuit decreases. Therefore, increasing the resistance will impede the flow of current, causing it to decrease.

Biomass is considered a renewable energy source because it is derived from organic materials such as plants, wood, and agricultural waste. These materials can be replenished through natural processes, making them sustainable in the long term. Biomass can be converted into various forms of energy, including heat, electricity, and biofuels, making it a versatile and environmentally friendly option.

The specific heat capacity of a substance is the amount of energy required to raise the temperature of 1 kg of that substance by 1 degree Celsius. In this question, we are given that the specific heat of sand is 664 J/(kg K). We are also given the mass of the sand (5 kg) and the change in temperature (25°C to 50°C). To calculate the energy needed, we use the formula: Energy = mass x specific heat x change in temperature. Plugging in the values, we get: Energy = 5 kg x 664 J/(kg K) x 25 K = 83000 J. Therefore, the correct answer is 83000 J.

A second class lever is the correct answer because in this type of lever, the load is located between the fulcrum and the effort. This means that the effort arm is always longer than the load arm, resulting in a mechanical advantage. In a second class lever, the load is moved in the same direction as the effort, which makes it easier to lift heavy objects. Examples of second class levers include a wheelbarrow and a nutcracker.

The current running through the lightbulb can be calculated using Ohm's Law, which states that current (I) is equal to voltage (V) divided by resistance (R). In this case, the voltage is 1.5 V and the resistance is 15 ohms. Therefore, the current is 1.5 V / 15 ohms = 0.10 amps.

Power is defined as the rate at which work is done or energy is transferred. It is calculated by dividing the work done by the time taken. In this case, Caleb does 2900 J of work in 7 seconds. Therefore, his power output can be calculated as 2900 J / 7 s = 414.3 watts.

The specific heat of a substance is defined as the amount of thermal energy required to raise the temperature of one kilogram of the substance by one degree Celsius. In this case, the concrete statue gained 90,000 J of thermal energy as it warmed up from 19°C to 40°C. To find the mass of the statue, we can use the formula:

Thermal energy = mass * specific heat * temperature change

Rearranging the formula, we have:

mass = thermal energy / (specific heat * temperature change)

Plugging in the given values, we get:

mass = 90,000 J / (600 J/(kg K) * (40°C - 19°C))

mass = 90,000 J / (600 J/(kg K) * 21 K)

mass = 7.14 kg

Therefore, the mass of the concrete statue is 7.14 kg.

A first class lever is the correct answer because it is a type of lever where the fulcrum is located between the effort and the load. In this type of lever, the effort is applied on one side of the fulcrum and the load is on the other side, with the fulcrum acting as the pivot point. This lever allows for a variety of movements and can be used to increase force or speed depending on the placement of the effort and load.

A third-class lever is the correct answer because it is a type of lever where the effort is applied between the fulcrum and the load. In a third-class lever, the load is closer to the fulcrum than the effort, which means that the effort arm is longer than the load arm. This type of lever provides mechanical advantage, allowing a smaller effort to move a larger load, but at the expense of increased effort distance.

The kinetic energy of an object is given by the equation KE = 1/2mv^2, where m is the mass of the object and v is its velocity. In this case, the mass of the roller coaster car is given as 755 kg and its velocity is 17.6 m/s. Plugging these values into the equation, we get KE = 1/2 * 755 kg * (17.6 m/s)^2 = 116,934 J. Therefore, the correct answer is 116,934 J.

Nuclear fission is the correct answer because it is the process that powers nuclear submarines. Nuclear fission involves the splitting of atomic nuclei, releasing a large amount of energy. This energy is harnessed in nuclear reactors on submarines to generate power and propel the submarine. Nuclear fusion, geothermal inversion, and cosmic implosion are not processes used to power nuclear submarines.

The process that powers the sun is nuclear fusion. Nuclear fusion is the process in which two or more atomic nuclei combine to form a heavier nucleus, releasing a large amount of energy in the process. In the sun, hydrogen nuclei combine to form helium, releasing a tremendous amount of energy in the form of light and heat. This process is what sustains the sun's energy output and allows it to shine.

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The resistance in a circuit can be calculated using Ohm's Law, which states that resistance is equal to voltage divided by current. In this case, the applied voltage is 120 volts and the current is 250 mA (or 0.25 A). By dividing 120 volts by 0.25 A, we get a resistance of 480 ohms.

The efficiency of a system is calculated by dividing the useful output energy by the input energy. In this case, the useful output energy is the work done by the motor to lift the load, which is equal to the force applied (3 N) multiplied by the distance lifted (6 m). The input energy is the electrical energy supplied to the motor, which is equal to the voltage (9 V) multiplied by the current (500 mA) multiplied by the time (60 s). By calculating these values and dividing the output energy by the input energy, the efficiency of the system is found to be 6.67 %.

The correct answer to number 2 on the paper test is 0.7.

The question asks for the answer to number 4 on the paper test. Among the given options, the only whole number is 6. Therefore, the correct answer is 6.

The mass of an object can be determined by dividing the net force acting on it by its acceleration, using the formula F = ma. In this case, the net force is given as 18 N and the acceleration is given as 4 m/s^2. By rearranging the formula, we can solve for mass: m = F/a. Plugging in the values, we get m = 18 N / 4 m/s^2 = 4.5 kg.

The answer is 83% because it is the only option that is a percentage. The other options, 120%, 17%, and 0.075%, are not valid percentages.

When resistors are connected in series, the total resistance is the sum of the individual resistances. In this case, the total resistance is 15 ohms + 15 ohms = 30 ohms. According to Ohm's Law, the current (I) flowing through a circuit is equal to the voltage (V) divided by the resistance (R), so I = V/R. Plugging in the values, we get I = 1.5 V / 30 ohms = 0.05 amps. Therefore, the correct answer is 0.05 amps.

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The power exerted by the truck can be calculated using the equation P = F * v, where P is power, F is force, and v is velocity. To find the force, we can use the equation F = m * a, where m is mass and a is acceleration. The acceleration can be calculated using the equation a = (vf^2 - vi^2) / (2 * d), where vf is final velocity, vi is initial velocity, and d is distance. Plugging in the given values, we can calculate the force and then substitute it into the power equation to find the power exerted by the truck. The correct answer is 76,562.5 watts.

A 60 watt lightbulb uses 60 joules of energy every second. In 3 hours, there are 60 seconds in a minute, 60 minutes in an hour, and 3 hours, so the total number of seconds is 60 x 60 x 3 = 10,800 seconds. Therefore, the total energy used by the lightbulb in 3 hours is 60 x 10,800 = 648,000 joules.

The given answer is 3 because it is the only whole number among the options provided. The other options are fractions or larger numbers.

When lamps are wired in parallel, the total resistance decreases because the current has multiple paths to flow through. Adding another lamp in parallel will provide an additional path for the current, resulting in a decrease in the total resistance. This means that more current will flow through the circuit, causing the total current to stay the same. The voltage across each lamp will also remain the same, as the lamps are still connected in parallel.

The current across R1 would be 0.003 A because according to Ohm's Law, the current flowing through a resistor is equal to the voltage across it divided by its resistance. Since the voltage across R1 is not given, we cannot determine the exact value of the current.