1.
Kinetic energy and potential energy are two types of
Correct Answer
C. Mechanical energy
Explanation
Kinetic energy and potential energy are two types of mechanical energy. Kinetic energy is the energy possessed by an object due to its motion, while potential energy is the energy stored in an object based on its position or state. Both forms of energy are associated with the movement or position of an object, hence falling under the category of mechanical energy.
2.
Which form of energy does the flowing water possess?
Correct Answer
C. Kinetic energy
Explanation
The correct answer is kinetic energy because flowing water is in motion, and kinetic energy is the energy of motion. When water flows, it possesses kinetic energy due to its movement.
3.
A body of mass 2 kg is dropped from a height of 1m. Its kinetic energy as it touches the ground is _______
Correct Answer
D. 19.6 J
Explanation
When an object is dropped from a height, it gains potential energy due to its position. As the object falls, this potential energy is converted into kinetic energy. The formula to calculate the kinetic energy of an object is KE = 1/2 * mass * velocity^2. In this case, the mass of the object is given as 2 kg. Since the object is dropped, its initial velocity is 0 m/s. When the object touches the ground, its velocity will be the maximum, which can be calculated using the equation v^2 = u^2 + 2as, where u is the initial velocity, a is the acceleration due to gravity (9.8 m/s^2), and s is the distance fallen (1 m). Solving for v, we get v = âˆš(0^2 + 2 * 9.8 * 1) = âˆš19.6 â‰ˆ 4.43 m/s. Plugging these values into the kinetic energy formula, we get KE = 1/2 * 2 kg * (4.43 m/s)^2 = 19.6 J. Therefore, the correct answer is 19.6 J.
4.
A unit of power is _______
Correct Answer
D. Joule per second
Explanation
A unit of power is measured in joules per second. Power is the rate at which work is done or energy is transferred, and it is calculated by dividing the amount of energy transferred by the time taken. The unit of energy is joules, and the unit of time is seconds. Therefore, the unit of power is joules per second.
5.
Power is a measure of the _______
Correct Answer
D. Rate of change of energy
Explanation
Power is a measure of the rate of change of energy. In other words, it quantifies how quickly energy is being transferred or transformed. Power is calculated by dividing the amount of energy transferred or transformed by the time it takes to do so. This concept is important in various fields, such as physics and engineering, as it helps to understand and analyze the efficiency and effectiveness of energy usage and transformations.
6.
Two objects of masses 1 x 10^{-}^{3} kg and 4 x 10^{-}^{3} kg have equal momentum. What is the ratio of their kinetic energies?
Correct Answer
A. 4:1
Explanation
The ratio of the kinetic energies of two objects is equal to the ratio of their masses. In this case, the mass of the first object is 1 x 10-3 kg and the mass of the second object is 4 x 10-3 kg. Therefore, the ratio of their masses is 1:4. Since the ratio of kinetic energies is the same as the ratio of masses, the ratio of their kinetic energies is also 1:4, which can be simplified to 4:1.
7.
A 40 newton object is released from a height of 10 m. Just before it hits the ground, its kinetic energy, in joules is _______
Correct Answer
D. 400
Explanation
The kinetic energy of an object can be calculated using the formula KE = 1/2 * m * v^2, where m is the mass of the object and v is its velocity. In this case, the mass of the object is not given, but since the object is released from a height, we can assume it is falling freely and neglect any air resistance. Therefore, at the moment just before it hits the ground, the object will have converted all of its potential energy into kinetic energy. The potential energy can be calculated using the formula PE = m * g * h, where g is the acceleration due to gravity and h is the height. Since the potential energy is converted into kinetic energy, we can equate the two equations: PE = KE. Solving for KE, we get KE = m * g * h. Plugging in the given values, KE = 40 * 9.8 * 10 = 3920 J. Therefore, the correct answer is 3920 J.
8.
If the speed of an object is doubled then its kinetic energy is _______
Correct Answer
B. Quadrupled
Explanation
When the speed of an object is doubled, its kinetic energy increases by a factor of four, which means it is quadrupled. This is because kinetic energy is directly proportional to the square of the velocity. Therefore, if the velocity is doubled, the kinetic energy will be four times greater than before.
9.
A man of mass 50 kg jumps to a height of 1 m. His potential energy at the highest point is (g = 10 m/s^{2})
Correct Answer
C. 500 J
Explanation
When the man jumps to a height of 1 m, his potential energy increases. Potential energy is given by the formula PE = mgh, where m is the mass (50 kg), g is the acceleration due to gravity (10 m/s^2), and h is the height (1 m). Plugging in the values, we get PE = 50 kg * 10 m/s^2 * 1 m = 500 J. Therefore, the correct answer is 500 J.
10.
The type of energy possessed by a simple pendulum, when it is at the mean position is
Correct Answer
A. Kinetic energy
Explanation
When a simple pendulum is at the mean position (equilibrium point), it has the maximum velocity and zero displacement. At this point, all the potential energy is converted into kinetic energy. Therefore, the correct answer is kinetic energy.
11.
An iron sphere of mass 30 kg has the same diameter as an aluminium sphere whose mass is 10.5 kg. The spheres are dropped simultaneously from a cliff. When they are 10 m from the ground, they have the same _______.(assume air resistance is negligible)
Correct Answer
A. Acceleration
Explanation
Since the iron and aluminum spheres have the same diameter, they experience the same gravitational force due to their equal distance from the ground. Therefore, they also have the same acceleration as they fall.
12.
A 1 kg mass has a kinetic energy of 1 joule when its speed is
Correct Answer
C. 1.4 m/s
Explanation
The kinetic energy of an object is given by the equation KE = (1/2)mv^2, where m is the mass of the object and v is its velocity. In this case, the mass is given as 1 kg and the kinetic energy is given as 1 joule. By rearranging the equation, we can solve for v: v = sqrt(2KE/m). Plugging in the values, we find that v = sqrt(2*1/1) = sqrt(2) â‰ˆ 1.4 m/s. Therefore, the speed of the 1 kg mass is 1.4 m/s when it has a kinetic energy of 1 joule.
13.
If air resistance is negligible, the sum total of potential and kinetic energies of a freely falling body _______
Correct Answer
D. Remains the same
Explanation
When air resistance is negligible, the only force acting on a freely falling body is gravity. As the body falls, it converts its potential energy (due to its height) into kinetic energy (due to its motion). According to the law of conservation of energy, the total mechanical energy (sum of potential and kinetic energies) remains constant in the absence of external forces. Therefore, the sum total of potential and kinetic energies of a freely falling body remains the same.
14.
An object of mass 1 kg has potential energy of 1 joule relative to the ground when it is at a height of _______.
Correct Answer
A. 0.102 m
Explanation
The potential energy of an object is given by the formula PE = mgh, where m is the mass of the object, g is the acceleration due to gravity, and h is the height of the object. In this case, the mass is 1 kg and the potential energy is 1 joule. We can rearrange the formula to solve for h: h = PE/(mg). Plugging in the values, we get h = 1/(1*9.8) = 0.102 m. Therefore, the object has a potential energy of 1 joule relative to the ground when it is at a height of 0.102 m.
15.
A young girl drags her favorite dolly by the hair at an angle of 55Â° to the ground for a distance of 4 m. If she pulls with a force of 3 N, what is the total work that she has done?
Correct Answer
A. Greater than 3 joules
Explanation
The work done by the girl can be calculated using the formula: work = force * distance * cos(angle). In this case, the force is 3 N, the distance is 4 m, and the angle is 55Â°. By plugging these values into the formula, we can calculate the work done. Since the angle is less than 90Â°, the cosine of the angle is positive, which means that the work done will be greater than 3 joules.
16.
Which of the following is a a scalar quantity?
Correct Answer
A. Temperature
Explanation
Temperature is a scalar quantity because it only has magnitude and no direction. Scalars are quantities that can be fully described by their magnitude alone, without any reference to direction. In contrast, force, acceleration, and velocity are vector quantities because they have both magnitude and direction.
17.
Which of the following is a a vector quantity?
Correct Answer
C. Displacement
Explanation
Displacement is a vector quantity because it has both magnitude and direction. It represents the change in position of an object from its initial position to its final position. In contrast, heat, length, and distance are scalar quantities as they only have magnitude and no specific direction associated with them.
18.
The number below is in scientific notation11.1 X 10^{2 }
Correct Answer
B. False
Explanation
The given number, 11.1 X 102, is not in scientific notation because the exponent should be a multiple of 10. In this case, the exponent is 102, which is not a multiple of 10. Therefore, the statement is false.
19.
The number below has five significant figures0.0110
Correct Answer
B. False
Explanation
The number 0.0110 has four significant figures because the zeros before the decimal point are not significant. Therefore, the statement that it has five significant figures is false.
20.
Conversion of chemical energy to electrical energy occurs in
Correct Answer
C. Batteries
Explanation
Batteries convert chemical energy into electrical energy through a chemical reaction. Inside a battery, there are two electrodes, one positive and one negative, immersed in an electrolyte solution. When the battery is connected to a circuit, a chemical reaction occurs at the electrodes, causing electrons to flow from the negative electrode to the positive electrode, creating an electrical current. This process allows batteries to store and provide electrical energy for various devices and applications.
21.
Conversion of chemical energy to mechanical energy occurs in
Correct Answer
B. Buses
Explanation
Buses have engines that run on chemical fuel, such as gasoline or diesel. These fuels undergo combustion, which releases energy in the form of heat. This heat energy is then converted into mechanical energy through the engine's internal combustion process. The mechanical energy is used to power the bus and move it forward. Therefore, the conversion of chemical energy to mechanical energy occurs in buses.
22.
Potential energy is converted to mechanical energy in
Correct Answer
D. Hydroelectric plants
Explanation
In hydroelectric plants, potential energy is converted to mechanical energy. This is achieved by harnessing the gravitational potential energy of water stored at a higher elevation, such as in a dam. The water flows down through turbines, causing them to spin and generate mechanical energy. This mechanical energy is then converted into electrical energy through the use of generators. Therefore, hydroelectric plants are able to convert the potential energy of water into usable mechanical energy.
23.
Chemical energy is converted to mechanical energy; and then converted to electrical energy in
Correct Answer
D. Generators
Explanation
Generators convert chemical energy, such as the energy stored in fossil fuels, into mechanical energy through combustion. This mechanical energy is then transformed into electrical energy through the use of electromagnetic induction. Solar cells, wind turbines, and wave power systems, on the other hand, directly convert renewable energy sources (sunlight, wind, and waves respectively) into electrical energy without the need for a generator.
24.
Energy required to move an object (mass = 10 kg) to a height of 10 meters in joules. Your answer should be a whole number. (number lang po, wala ng units)
Correct Answer
980
980 J
Explanation
The energy required to move an object to a height of 10 meters is given by the formula: potential energy = mass * gravity * height. In this case, the mass of the object is 10 kg, the height is 10 meters, and the acceleration due to gravity is approximately 9.8 m/s^2. Plugging these values into the formula, we get: potential energy = 10 kg * 9.8 m/s^2 * 10 meters = 980 J. Therefore, the correct answer is 980 J.
25.
Two forces are acting on a stationary book on a table
Correct Answer
A. True
Explanation
The statement is true because if a book is stationary on a table, it means that the forces acting on it are balanced. According to Newton's first law of motion, an object at rest will remain at rest unless acted upon by an external force. Therefore, if the book is not moving, it implies that the forces acting on it, such as the gravitational force pulling it downwards and the normal force exerted by the table upwards, are equal in magnitude and opposite in direction, resulting in a state of equilibrium.
26.
Physics involve the study of the atom
Correct Answer
A. True
Explanation
Physics is a branch of science that deals with the study of matter and energy, including their properties and interactions. Atoms are the basic building blocks of matter, and understanding their structure and behavior is a fundamental aspect of physics. Therefore, it is correct to say that physics involves the study of the atom.
27.
Discovered the law of motion
Correct Answer
C. Isaac newton
Explanation
Isaac Newton is the correct answer because he is widely credited with discovering the laws of motion. Newton's three laws of motion describe the relationship between an object and the forces acting upon it. These laws form the foundation of classical mechanics and have had a significant impact on our understanding of motion and the physical world. Galileo Galilei made important contributions to the study of motion, but he did not discover the laws of motion. Schrodinger is known for his work in quantum mechanics, while Aristotle's understanding of motion was based on philosophical ideas rather than scientific experimentation.
28.
The power exerted by a man who uses 10 newtons to push a 5.0 kg box is ____ a horse which pulls a 1.0 kg with a force of 25 N.
Correct Answer
D. It depends on the time
Explanation
The power exerted by a person or a horse is calculated by dividing the work done by the time taken. In this case, the work done by the man can be calculated as the product of the force applied (10 N) and the distance moved by the box. Similarly, the work done by the horse can be calculated as the product of the force applied (25 N) and the distance moved by the object. Since the distance moved is not given and the power depends on the time taken, it is not possible to determine whether the power exerted by the man is greater than, less than, or equal to the power exerted by the horse.
29.
1st law of motion has to do with
Correct Answer
B. Inertia
Explanation
The first law of motion, also known as the law of inertia, states that an object at rest will stay at rest and an object in motion will stay in motion with the same speed and direction unless acted upon by an external force. Inertia is the property of matter that resists changes in its motion. Therefore, the correct answer is inertia because the first law of motion is directly related to the concept of inertia.
30.
If you push against the wall, the wall pushes the same force against you. This is an application of the 2nd law.
Correct Answer
B. False
Explanation
This statement is incorrect because it does not accurately represent Newton's 2nd law of motion. According to the 2nd law, when an object exerts a force on another object, the second object exerts an equal and opposite force on the first object. In the given statement, it is suggested that the wall pushes the same force back on the person pushing against it, which is not true. The wall only exerts a normal force on the person, not an equal and opposite force.