Physics - MCAT Chemical and Physical Foundations of Biological Systems

The speed of sound is dependent on the temperature of the transmitting medium. The speed of light is not.

The speed of sound depends on both the medium’s density and resistance to compression. We do not have enough information to solve for V2 in terms of V1.

The total energy of a simple harmonic oscillating system can be determined by the equation . A is the amplitude of the oscillation, k is the spring constant, and E is the total energy. Plugging in values given by the equation, the total energy is equal to 0.1J.

The energy in a spring is given by the equation , where is the spring constant and is the displacement from the equilibrium position. The energy is transferred into kinetic energy in the pinball.

The kinetic energy in the pinball is found using the equation .

Now that we have kinetic energy, we can find the equal energy that was stored in the spring to begin.

Using the equation we can find the frequency of the soundwave.

Conservative forces are forces that do not lose energy to heat, sound, or light. Of these answers, energy is completely conserved and transferred from kinetic energy to potential energy, or vice versa. Gravitational forces, electrostatic forces, and elastic forces all work by providing a potential that will work in the same direction as the motion of an object or particle, allowing kinetic and potential energy to interconvert. Frictional forces lose energy as heat when sliding across a surface, and the more force (the more rough the surface), the more energy that is lost.

Gravitational potential energy is determined using the equation , with being the mass of the object, being the gravitational acceleration, and being the height of the object relative to the ground. Because we know the length of the ramp and the angle of the ramp, we can solve for the box's height above the ground.

Now that we have the height, we simply plug the given values into the equation.

Friction is a non-conservative force, meaning that the work it does depends on the path taken by the object. For example, moving a brick in a long zig-zag across the table will generate more heat from friction than moving it in a straight line across the table.

Electric and gravitational forces are conservative. This can be tested by knowing a constant equation to calculate the energy associated with these forces; such equations are applicable regardless of path. No such equation exists for frictional energy.

Consider a beaker containing water. The molecules at the surface of water interact with fewer molecules than the molecules at the center of the beaker. The surface molecules have no water molecules above them, whereas the molecules in the center of the solution interact with molecules in all directions. Since the surface molecules have fewer interactions, the interactions between these molecules are much stronger than the interactions of a center molecule; fewer interactions have opposing counterparts, resulting in stronger forces.

Recall that surface tension can be defined as the resistance to increasing surface area. This means that the surface area is minimized due to surface tension. Of all the geometrical shapes, spheres have the lowest surface area to volume ratio; therefore, surface tension forces water droplets to take spherical shapes. Surface tension occurs due to the intermolecular forces between liquid molecules. These intermolecular forces between molecules are cohesive, preventing the spreading of water molecules.

It is harder to move an object that is floating on water than an object submerged in water. This occurs because the interactions between the molecules at the surface are stronger than the interactions below the surface. Moving an object involves moving the water molecules around it. Since it is harder to move molecules at the surface (stronger interactions), it is harder to move an object at the surface. An object floating on water will have more resistance to motion.

Surface area is directly related to the number of molecules at the surface. An increase in surface area will lead to an increase in the number of molecules at the surface. Since surface tension is the ability of a fluid to resist an increase in surface area, the surface area decreases due to increased surface tension. This means that the amount of molecules at the surface also decreases due to surface tension.

The image distance for a plane mirror is always equal to the object distance because the magnification is 1.

If the object and image are the same distance from the mirror and magnification is 1, then as the object approaches the mirror at a certain speed, the image is approaching the plane mirror at the same speed, therefore you approach the image more quickly than you approach the mirror, since you travel 5m/s toward the mirror and the image travels 5m/s toward the mirror.

This question deals with an application of optics. In this case we have a farsighted person and a near sighted person. The farsighted person would use a convex lens, which is a converging lens. This would allow all of the rays of light to converge on a single point, allowing them to heat the object up and start a fire. Wendy’s glasses are diverging lenses, which would cause the rays to separate.

This asks us to understand the vector components of velocity. Remember that the final velocity is the hypotenuse of a triangle (solved to be 10m/s in the previous problem), and that by knowing the hypotenuse value we can solve for the horizontal component by using cosine.

vx = (10m/s)(cos(45o)) = 7.1m/s

This question also asks us to understand the vector components of velocity. Remember that the final velocity is the hypotenuse of a triangle, and that by knowing the hypotenuse value (solved as 10m/s in a previous problem) we can solve for the vertical component using sine.

vy = (10m/s)(sin(45o)) = 7.1m/s

A decrease in pressure means a decrease in gas particle collisions. The only option that would not cause a decrease in collisions is adding moles of a different gas. Even though different molecules are added, there will be greater pressure as particle collisions will be more frequent.

Reducing temperature slows the gas particles, thus decreasing the frequency of collisions. Similarly, increasing the volume of the container and removing particles will cause a decrease in collisions, and subsequent pressure.

Without an additional force acting in the horizontal direction during flight (we are told we can neglect air resistance), there is no acceleration. Remember that Newton's second law, F = ma, requires that a force act on an object to produce acceleration. Here, we have no additional force and thus no acceleration.

Both the length of the pendulum's string and the angle of displacement affect the maximum velocity of the pendulum. Increasing the length of the pendulum's string and increasing the angle of displacement both increase the distance the pendulum must travel in a single period, increasing its potential energy at its maximum height, and therefore the maximum velocity at its lowest point.

The key to answering this question is to recall the following important formula for a simple pendulum: .

Measurements of real gases deviate from ideal gas predictions because intermolecular forces and the volume of the particles themselves are not taken into consideration for ideal gases. The volume of the space between particles is considered for ideal gases and does not contribute to deviation from ideal gas behavior.

Attraction between molecules causes real pressure to be slightly less than ideal pressure, while the volume of gas particles causes real volume to be slightly greater than ideal volume.