MCAT Physics Practice Questions

Many biological membranes have an uneven distribution of charged ions on each side, creating a potential difference. One example is the resting potential of neurological membranes. A particle with a charge equal to that of 3 × 106 electrons travels through a potential difference of 82 mV. How much energy is gained by this particle? 3.0 × 10^3 eV 3.0 × 10^6 eV 2.5 × 10^5 eV 2.5 × 10^8 eV

This question essentially tests the definition of an electron volt. An electron volt is the energy gained by a particle with the charge of an electron when that particle is moved through 1 volt. Therefore, a particle with the charge of 3 × 10^6 electrons moving through a potential of 82 × 10^-3 V will gain an energy of 2.46 × 10^5 eV.

For a three second period of time, a 50 kg wooden crate slides across the concrete floor at exactly 5 m/s. The coefficient of kinetic friction between the wooden crate and the concrete floor is 0.2. What is the net force of this crate during this three second period? 500 N 50 N 0 N 100 N

0N Since there is a constant velocity, there is no net acceleration and no net force.

Which of the following relationships between measurement error and overall error is correct? A. Unreliable data leads to confounding B. Invalid data leads to confounding C. Unreliable data leads to bias D. Invalid data leads to bias

D. Invalid data leads to bias Data that is off in a systematic way will cause bias. This type of data error is an example of lack of validity (or accuracy). Unreliable data suffers from random, not systematic, error. Confounding arises from errors in data analysis, not data collection.

An 8 kg block is placed at the top of a plane inclined by 30 deg. with a coefficient of kinetic friction of 0.1. What is the block's acceleration down the ramp? 5-√3/2 m/s^2 5-√5/2 m/s^2 10-√3/2 m/s^2 10-√5/2 m/s^2

F = mgsinθ - μk mgcosθ 5-√3/2 m/s^2

Which of the following statements correctly identifies an example of the respective scalar or vector product processes? I. Vector and scalar : torque II. Vector and vector : magnetic force III. Scalar and scalar : power III only I only II and III I and II

II and III A scalar multiplied by a scalar will produce another scalar. For instance, distance divided by time is equal to speed, which is a scalar. In the case of power, energy divided by time is equal to power. Statement III is true. A vector multiplied by a scalar is representative of the scalar product or the dot product and will always produce a vector. The scalar product of two vectors A and B can be constructed by taking the component of A in the direction of B and multiplying it times the magnitude of B, and it can be expressed as ABcosθ. Torque is not an example of the scalar product of vectors since it is equal to rFsinθ. A correct example of the dot product would be work, which is equal to Fdcosθ. Therefore, statement I is not true. Vector multiplied by a vector is representative of the vector product or the cross product and will produce a vector or scalar. The magnitude of the vector product of A and B can be constructed by taking the product of the magnitudes of A and B multiplied by the sine of the angle between them. Magnetic force is an example of the vector cross product, so statement II is true. Therefore, the correct answer is that statements II and III are true.

Which of the following statements is true regarding a rider in a roller coaster cart moving with a constant speed through a loop? The sum of all the forces acting on the rider is zero. There are two forces acting on the rider, but neither does any work on the rider. The rider is accelerating. Gravity is the only force doing work on the rider.

Let's evaluate the situation. A roller coaster is moving with a constant speed through a loop. In terms of circular motion, this constant speed represents the tangential velocity. In a vertical loop, there are 2 forces acting on the object: the normal force and gravity. When a force acts perpendicular to the displacement of the object, no work is done. Only at the bottom and the top of the vertical loop is gravity perpendicular to the displacement. If the sum of all the forces acting on the rider is zero, then the rider would be either moving in a straight line at a constant velocity or not moving at all. When an object is undergoing circular motion, the magnitude of the velocity or speed is constant, but constantly changes direction. Therefore, the object is accelerating because of the changing direction.

If the frequency of the first harmonic is 100 Hz, what is the period of the second harmonic? 0.005 sec 0.01 sec 50.0 sec 200.0 sec

T = 1/f If the first harmonic has a frequency of 100 Hz, then the second harmonic has a frequency of 200 Hz. The period the corresponding to 200 Hz is 1/200 s^-1 = 0.005 sec

Which of the following is a true statement concerning speed, velocity, and acceleration? A. If the displacement of an object is zero, the speed must be zero B. An increase in speed must mean the object experiences acceleration C. Speed is a vector quantity representing magnitude and direction D. An object cannot accelerate if it is moving at a constant speed

The vector quantity representing magnitude and direction is velocity, not speed Because speed is not a vector quantity, constant speed cannot tell us direction of an object. Therefore you can move at constant speed but still accelerate by changing direction. Displacement of an object could equal zero simply by moving in a circle. If your initial and final positions are the same, your displacement is zero but your speed is not. An object can only experience an increase in speed if it is accelerated

The explanation for the fact that radioactive isotopes of an element exhibit the same chemical behavior as the stable isotopes of the element is that each has the same: atomic number number of neutrons mass number atomic weight

atomic number

An elevator's motion is through the action of a single cable. The elevator has a gravitational force of 2000 N. When the elevator is moving downwards at a constant velocity, how much tension is in this cable? equal to 2000 N slightly less than 2000 N greater than 2000 N close to 0 N

equal to 2000N Drawing a free-body diagram of a elevator in motion will elucidate the forces on the elevator The forces on the elevator when it is moving downwards at a constant velocity are the gravitational force and the force due to the tension on the cable. If the elevator is moving at constant velocity, then there is no net acceleration and no net force. The tension in the cable must equal the gravitational force of the elevator.