Physical Science Answer Key, Part 1

1. The correct answer is choice "B" as the amount of work that would be performed by a 25 Newton force that pushed a 75 kilogram rock or any other object 15 meters would be 375J. This is because the work performed by a constant horizontal force is equal to the force in Newtons multiplied by the distance that the object was pushed in meters. In other words, for this particular situation, the amount of Work in joules = the amount of Force in Newtons multiplied by the Distance traveled in meters or W = F * d. As a result, the correct answer to the problem is 25 Newtons * 15 meters or 375 joules. It is important to note that the weight of the object actually has no bearing on the amount of work performed by the force and that this formula only works for a constant horizontal force and not for a force pushing an object at an angle.

2. The correct answer is choice "C" as Boyle's gas law, written by Robert Boyle in 1662, states that the pressure exerted by a certain amount of gas is inversely proportional to the volume of the gas as long as the temperature remains constant. In other words, as long as the temperature does not change, the pressure that a particular gas exerts will increase as the volume of the gas decreases. This also means that the pressure that a particular gas exerts will decrease as the volume of the gas increases. It is important to note, however, that this law only applies to a fixed amount of gas in a closed system at a constant temperature. The relationship between the pressure and volume of a gas may deviate significantly from Boyle's law in situations where the temperature changes frequently or in situations where the gas is able to escape.

3. The correct answer is choice "B" as Charles' gas law, written by Jacques Charles in 1787, states that the volume of a certain amount of gas is directly proportional to the temperature of that gas as long as the pressure remains constant. In other words, as long as the pressure does not change, the volume of a gas will increase as the temperature increases and the volume of gas will decrease as the temperature decreases. It is important to note, however, that this law only applies to a fixed amount of an ideal gas in a closed system at a constant pressure. The relationship between the volume and temperature of a gas may deviate significantly from Charles' law in situations where the pressure changes frequently or in situations where the gas is able to escape.

4. The correct answer is choice "C" as the ideal gas law states that the current state of an ideal gas depends upon the volume, pressure, and temperature of that gas. In other words, the ideal gas law is basically a combination of Boyle's gas law and Charles' gas law that simply states that there is a relationship between the volume, pressure, and temperature of a particular ideal gas or a mixture of ideal gases. The relationship between volume, pressure, and temperature can be expressed mathematically using the formula pV = nRT, where p refers to the pressure, V refers to the volume, n is the amount of gas present, R is the gas constant, and T is the temperature. The amount of gas present is measured in moles and the temperature is measured in Kelvin for the purposes of this formula. It is important to realize, however, that the ideal gas law only applies to ideal gases and gases that are at extremely low temperatures or extremely high pressures may deviate significantly from this formula.

5. The correct answer to this particular question is hydrochloric acid, which is choice "A," because hydrochloric acid is actually the only strong acid included on the list. A strong acid is considered to be any acid that will become almost completely ionized if it is dissolved in water. In other words, if the atoms and molecules that make up the acid can be almost completely broken down into ions by dissolving the acid in water, then the acid is considered to be a strong acid. The process of the acid atoms and molecules breaking down into smaller ions is also referred to as dissociation and the level of dissociation for a strong acid must be close to 100%. It is important to note, however, that in order for an acid to be considered strong the level of dissociation must be close to 100%, but it does not necessarily need to be exactly 100%.

6. The correct answer to this particular question is calcium hydroxide, which is choice "D," as calcium hydroxide is actually the only strong base included on the list. A strong base is considered to be any base that will become almost completely ionized if it is dissolved in water. In other words, if the atoms and molecules that make up the base can be almost completely broken down into ions by dissolving the base in water, then the base is a strong base. The process of the atoms and molecules that make up the base breaking down into smaller ions can also be referred to as dissociation and a base is considered to be a strong base if the level of dissociation is close to 100%. It is important to note, however, that the level of dissociation does not necessarily need to be exactly 100%, but rather, close to 100% for a base to be considered a strong base.

7. The correct answer is choice "C" as the amount of potential energy for the cement block in this particular situation is 15,200J. This is because the potential energy of an object at a certain height is equal to the mass or weight of the object multiplied by the height of the object multiplied by the acceleration of gravity. In other words, the potential energy in joules = the mass of the object in kg * the height of the object measured in meters * the acceleration of gravity in m/s/s or PE = m*g*h. The acceleration of gravity on Earth is approximately 10 m/s/s so the potential energy of the cement block is equal to 10 kg * 10 m/s/s* 152 m or 15,200 joules.

8. The correct answer is choice "C" as the zeroth law of thermodynamics states that if two thermodynamic systems are each in thermal equilibrium with a third system, then the two systems are in thermal equilibrium with each other. In other words, if you have two heat systems that each contain the same amount of heat energy as a third system, then the two heat systems have the same amount of heat energy as each other as well. This is basically a very complicated way of saying that if System A is equal to System C, and System B is equal to System C, then System A must be equal to System C as well. The other options are actually incorrect for this particular question as they describe other laws of thermodynamics, but not the zeroth law.

9. The correct answer is choice "A" as Newton's first law states that an object in motion will stay in motion and an object at rest will stay at rest unless an outside force acts upon it. For example, a ball sitting on a level floor will not roll unless something else, such as a person hitting it, causes the ball to roll. However, this same ball, if someone caused the ball to start rolling, will not stop rolling unless something else, such as a wall or the force of gravity, causes it to stop. It is important to note that choice "B" may appear to be correct, but it is actually incorrect because it does not consider the fact that an outside force acting on the object can cause the object to move or stop moving.

10. The correct answer is choice "D" as Newton's third law states that for every action there is an equal and opposite reaction. For example, if a ball is sitting on the floor and someone kicks it, the person is applying the force of his or her foot to the ball and the ball, in turn, will apply its force to the individual's foot. In other words, the individual that kicks the ball is actually the one exerting the force that causes the ball to move. However, at the same time, the ball is pushing against the individual's foot as he or she makes contact with the ball so pressure is actually being applied to both the ball and the individual's foot as the individual kicks the ball. If the individual hurts his or her foot while kicking the ball, it is actually the force exerted by the ball on the individual's foot that is causing the pain and not the force exerted by the foot itself so there are actually two forces acting in opposite directions.