|
|
|
|
Solutions for physics questions
Answers and explanations for MCAT physics sample questions.
1. This is considered an easy question in Periodic motion. Let's refer to the object as the spring itself, since they are tightly connected. The restoring force of a spring is directly proportional to the distance from the point of equilibrium. As an oscillating spring arrives at its maximum stretch, it is located as far as possible from the point of equilibrium, and at this point, the force that acts upon it is the greatest, resulting in a maximum acceleration. On the other hand, this maximal force prevents the additional movement in the opposite direction and brings the velocity to zero. This makes statement I true.
As for the second statement, think of the moment at which the spring approaches its equilibrium point. The force decreases, and so does the acceleration, but the velocity increases and reaches its maximum at the point of equilibrium. Therefore, B is the correct answer.
2. This question deals with chemical equilibrium. In this reaction, each mole of POCl3 creates one mole of POCL and one mole of Cl2 . Therefore, if the concentration of the reactants at equilibrium equals 0.15M, then this is the amount of POCl3 that was lost. It is a common mistake to think that the fact that there are two products in equilibrium with 0.15M then the reactant lost the sum of these concentrations - 0.30M. Now we can write the equilibrium constant equation:
Therefore, B is the correct answer.
3. In order to have the pole suspended parallel to the ground, the works that each object exerts along the pole must be canceled, or in other words, their sum must equal zero. This situation would have occurred if we only had a pole and a rope tied to its middle, which is its center of mass. We can use the sum of all works performed by each object (the pole and each cap) so that the distance will be taken into account.
Let's assign the distance between the right cap and the rope as X, and mark a hypothetic point which represents the pole's middle. Then, in order to have an equality of works from both sides of the rope, the sum of works performed to the left of point X must be quantitatively equal and opposite in direction to the sum of works to the right of X. We can therefore write:
Therefore, C is the correct answer.
4. After cutting the magnets and turning both 180°, the new poles are as depicted below:
It can be seen that the north pole will attract the south pole and the forces they will exert are in opposite directions. The first statement is thus incorrect, since the forces they exert are not in the same direction.
The second statement is also incorrect since the forces exerted will cause attraction and not rotation (there is no torque for a spin).
As for the third statement, the electron represents a charge that moves in a magnetic field, and thus must feel a magnetic force. To have a force pointing outside the screen means that the electron is moving upwards the plane of the screen:
Thus, the direction of the magnetic force points outside the plane of the screen, which makes A the correct answer.
Back to MCAT physics
Try more MCAT sample questions
Learn more about our MCAT prep
|
Free Practice
Critical Reasoning TestData Sufficiency TestReading Comp. TestFree MCAT TestFree LSAT Test
|