Physics

A 400 -gram metal needs 720 calories of heat to raise its temperature from 30°C to 50°C. Calculate for the specific heat capacity of the metal.

0.09 cal/g C

At a traffic light intersection, Car A with a mass of 1500 kg comes to a full stop. Shortly after, Car A is hit behind by Car B, which has a mass of 2000 kg. After çollision, both cars move together at 10.0 m/s squared. How fast was Car B moving before the collision? (Hint: Use the Conservation of Momentum principle)

17.5 m/s

A system of pulleys is used to lift a 50 -kilogram load to a 125 -meter tall building. It was found that 250 meters of rope is pulled in lifting the load to the top of the building. What amount of force was exerted in pulling the rope if the efficiency of the system is 75% ?

327 N

A man stands in front of two plane mirrors joined together at a certain angle. He noticed that there are nine (9) images formed on these mirrors. What is the angle between the two mirrors?

36°

Two cords are supporting a 200 -kilogram object as shown in the figure below. Find the measure of the angle that the cord, A, makes with the horizontal if it exerts a tension of 2260 N.

60°

How much heat is needed to raise the temperature of 500 grams of lead from an initial temperature of 35°C to a final temperature of 75°C? (c = 0.031 cal/g.° C)

620 cal

Ryan is standing 3.6 m from a plane mirror. How far is Ryan's image from him?

7.2 m

A spherical mirror has a focal length of +5 centimeters. Find the location of the image for an object placed 15 centimeters away from the mirror and state whether the image is enlarged or diminished.

7.5 cm diminished

How long will it take for a runner to finish a marathon race of 5000 meters if he can maintain an average velocity of 5.5 m/sec ?

909 seconds

A flashlight uses a concave mirror to operate. Relative to the mirror, where should the bulb of a flashlight be placed to generate the maximum amount of light?

At the focus of the mirror

Two identical objects are launched from the same height at the same time. One is dropped and the other is thrown horizontally. Which hits the ground first? Neglect air resistance.

Both objects hit the ground at the same time

When you put some ice or ice-cold water inside a pitcher, you will notice that after some time small drops of water appear on the outer surface of the pitcher. What is responsible for this phenomenon?

Condensation These water drops are formed by the condensation of the water vapor present in the air. When the water vapor in air comes in contact with the outer surface of the pitcher, which has a lower temperature, the water vapor then condenses and turns into liquid. This is the same phenomenon observed when dew forms on the surface of trees, plants and grass overnight. Water vapor in the air condenses to dew because of the cool of the night.

The capacitance of a capacitor can be increased by inserting an insulating material between the plates. This material is called a

Dielectric materials are insulating materials which can withstand electric fields larger than those that can cause air to break down. The insertion of dielectric material reduces the distance between the two plates which results to the increase in the capacitance.

In the formation of a rainbow, sunlight passes through raindrops, and the drops act as tiny prisms. What properties of light are involved in the formation of the rainbow?

Dispersion, Interference, and Diffraction

A satellite is on orbit around the earth at a distance, d, from the center. The force due to gravity on the satellite is F. When the satellite increases its distance from the center of the earth three (3) times, the force of gravity on the satellite would be:

F/9

A lady is standing between two parallel mirrors on which the reflecting surfaces are facing each other. How many images will be formed?

Infinite

When two plane mirrors are joined together, the number of images formed depends on the angle between the two plane mirrors. It was observed that 45° produces 7 images, 60° produces 5 images, 90° produces images and 180° produces 1 image. This shows that the number of images produced is

Inversely proportional to the angle between the two mirrors.

When a ball is thrown straight up into the air, which of the following describes its motion at the highest point of its path?

It has zero velocity.

A 50 -gram stone was thrown vertically upward. What can be said about the total mechanical energy of the stone at the highest point of its path? (Neglect air resistance.)

It is equal to the potential energy of the stone.

A blue transparent glass appears to be blue when illuminated by a white light because

It transmits only blue light

GM The speed of a satellite revolving around a planet is given by v = .When the orbital radius of a satellite will be increased four times, what happens to the speed of the satellite?

It will be halved.

Which of the following describes an atom with 6 protons and 7 neutrons?

Its atomic number is 6. The atomic number refers to the number of protons found in the atom. Tip! You need to be able to differentiate the atomic number from the mass number or atomic mass, which is the number of protons plus the number of neutrons in the atom. Hence, in the given atom, the mass number is 6 + 7 = 13

The odometer of a car reads 67321.0 km when the clock shows the time 6 : 30 AM. What is the speed of the car if at 6: 50 AM, the odometer reading has changed to 67336.0 km ?

Speed = distance travelled / time Speed = (67336.0 km - 67321.0 km)/0.3 hr Speed = 15 km/0.3 hr Speed = 45 km/hr

Which of the following does NOT affect the gravitational potential energy of an object?

Speed of the object Gravitational Potential Energy is energy due to the position. It is given by the formula: PE = mgh ; where PE = Potential Energy, m = mass of the object, g = acceleration due to gravity and h = height with respect to a reference point. Thus, it does not depend on the speed of the object.

Which of the following is a restatement of the Law of Conservation of Energy?

The 1st Law of Thermodynamics

When light travels through two different medium such as air and water, it undergoes refraction. When light refracts, it changes its

direction and speed Refraction is the apparent bending of light rays as they pass through two different media. When light refracts, it experiences a change in speed and direction. This is due to the difference in the optical density of the two media. When light passes from a substance of lower optical density to one of higher optical density, it slows down and bends towards the normal line (i.e. air to water). The reverse is true when light passes from a substance with a higher optical density to one with a lower optical density (i.e. water to air).

The reason why a magnifier is made of a convex lens instead of concave lens is that a convex lens has the ability to produce an image which is

erect and enlarged.

If you squeeze a balloon to one fourth its original size, the pressure inside

increases four (4) times

When the distance between two protons is doubled, the electrical repulsion force between them is

quartered

Which of the following phase change involves sublimation?

solid to gas Sublimation is a phase change process in which a solid becomes a vapor without passing the liquid phase.

If two different systems are put in contact with one another so that heat can flow from one system to the other, heat will continually flow until the two systems have the same

temperature.

The frequency -- energy relationship is given by E = hf, where E = energy, h = Planck's Constant and f = frequency. Which of the following colors in the electromagnetic spectrum contains the highest energy?

violet

A man pushes a crate 4 m across the floor with a force of 15 N. How much work is done by the man?

60 J

How many images are produced when an object is placed in front of two plane mirrors at a 30 -degree with each other?

11 The number of images that can be produced by two mirrors at a certain angle between them is given by # of images = (360°/ angle bewteen the mirrors ) - 1; thus we have: # of images = (360°/30°) -1 # of images = 12 - 1 # of images = 11

In a car race, a car initially at rest accelerates at 2.5 m/s squared within the first 50.0 seconds. Calculate the velocity of the car at the end of the first 50.0 seconds.

125 m/s

How much heat required to raise the temperature of 500 grams of water by 10° C? (500 grams of water is about 2 cups)

5000 cal

Three identical 3 -ohm resistors are connected in parallel as shown in the diagram below. What is the total power consumed by this network of resistors? 24 V-

576 watts

Which temperature scale labels the boiling point of water at 100 degrees and the freezing point of water at 0 degrees?

Celsius Scale Water boils temperature of 100 degrees Celsius and freezes at 0 degrees Celsius. Water boils at a temperature of 373 K (Kelvin) and freezes at 273 K. Water boils at a temperature of 212 degrees Fahrenheit and freezes at 32 degrees Fahrenheit.

Which of the following gas laws relates the volume and temperature of gases under constant pressure?

Charles' Law

Which of the following gas laws relates the volume and temperature of gases under constant pressure?

Correct answer: Charles' Law Charles' Law-- This law is about volume and how it relates to temperature, so constant pressure is assumed (i.e., the pressure does not change). This law says that volume is directly proportional to absolute temperature (VaT). The temperature in this law is measured in Kelvin. This law implies that as volume increases, temperature also increases at the same rate. Option Boyle's Law This law is about pressure and volume relationships, therefore it assumes constant temperature (i.e., the temperature does not change). This law states that pressure and volume are inversely proportional (Va1/P). That means that as the pressure becomes larger, the volume becomes smaller. Option - Gay-Lussac's Law -- This law is about how pressure and temperature are related, which means the law assumes a constant volume of gas (i.e., the volume does not change). This law says that pressure is directly proportional to temperature (PaT). Simply stated, this law implies that as pressure increases, temperature also increases at the same rate. Option Newton's Laws refer to laws of motion for objects, and not the behavior of gases.

Which of the following gas laws relates the pressure to the temperature of gases under constant volume?

Correct answer: Gay-Lussac's Law Gay-Lussac's Law This law is about how pressure and temperature are related, which means the law assumes a constant volume of gas (i.e., the volume change). This law says that pressure is directly proportional to temperature (PaT). Simply stated, this law implies that as the pressure increases, the temperature also increases at the same rate. Option - Boyle's Law This law is about pressure and relationships, therefore it assumes constant temperature (i.e., the temperature does not change). This law states that pressure and volume are inversely proportional (Val/P). That means that as the pressure becomes larger, the volume becomes smaller. Option Charles' Law-- This law is about volume and how it relates to temperature, so constant pressure is assumed (i.e., the pressure does not change). This law says that the volume is directly proportional to the absolute temperature (VaT). The temperature in this law is measured in Kelvin. This law implies that as the volume increases, the temperature also increases at the same rate. Option - Newton's Laws refer to laws of motion for objects, not to the behavior of gases.

When white light reaches an opaque material, which of the following is/are most likely to happen? I. All the colors will be reflected. II. Some colors will be reflected. III. All the colors will be absorbed. IV. Some light will be transmitted.

I, II, and II White light is composed of all the colors. When white light reaches an opaque object, three things may happen: I) All the colors in the white light will be reflected and the object will appear to be white; II) Some colors will be reflected and the object will appear to be colored; or III) All the colors will be absorbed and the object will appear black. No light will be transmitted since opaque materials are materials that do not allow light to pass through them.

Which of the following statements is true about momentum?

Momentum is a motion quantity measured as a product of an object's mass and its velocity (momentum = mass x velocity)

Which of the following is a restatement of the Law of Conservation of Energy?

The 1st Law of Thermodynamics. When heat flows to or from a system, the system gains or loses an amount of energy equal to the amount of heat transferred". The First Law states that energy cannot be created nor destroyed. The amount of energy loss in a steady-state process cannot be greater than the amount of energy gained. This is how the law of conservation of energy relates to a thermodynamic system. The 2nd Law of Thermodynamics/Entropy. In a simple manner, the second law states that "energy systems tend to increase their entropy rather than decrease it" (Entropy refers to the state of disorder in a system, and it is not an actual law). This can also be stated as "heat can spontaneously flow from a higher-temperature region to a lower-temperature region, but not the other way around." The 3rd Law of Thermodynamics is concerned with the entropy of a perfect crystal at absolute zero temperature. It implies that it is impossible to cool a system all the way to exactly absolute zero.

A projectile is thrown upward. Which of the following is NOT a description of the projectile at the maximum height

The acceleration will decrease until it reaches zero. WRONG Rationale: A projectile in motion (near the surface of the earth) always experiences a constant downward acceleration of 9.8 m/s which is uniform everywhere at any time (The acceleration will be directed downward). and (The acceleration will still be 9.8m/s). The acceleration never changes, so (The acceleration will decrease until it reaches zero) is the incorrect description. This causes the projectile to first ascend with decreasing vertical speed, then momentarily at rest (The velocity will momentarily be zero), and lastly returns with increasing vertical speed while plummeting.

A car travels around circular track at a constant speed. Which of the following statements is TRUE?

The car is accelerating.

Which mode of heat transfer explains why you can place your finger beside a candle flame without harm but not above the flame?

convection