MCAT Physical : MCAT Physical Sciences
Study concepts, example questions & explanations for MCAT Physical
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Example Questions
Example Question #2 : General Principles
A runner completes a lap on a circular track in three minutes. The track has a radius of 210ft. The runner ran at a constant speed around the track.
Which of the following statements is true?
The runner's total distance traveled is equal to the runner's total displacement
The runner's average speed is greater than the runner's average velocity
The runner never accelerated while running around the track
The runner's average velocity is
The runner's average speed is greater than the runner's average velocity
This is a question that helps you see how displacement and velocity compare to distance and speed, respectively. Remember that the runner starts and stops at the same point on the track, so her total displacement is zero feet.
Since 
This is also important to remember! Since the runner changed direction on the track, she accelerated and decelerated accordingly based on her position on the track. She did not have a constant acceleration.
Example Question #1 : Ap Physics 1
Three blocks (in left-to-right order: block A, block B, block C) are pushed along a frictionless horizontal surface by a 50N force to the right, which acts on block A.
If the masses of the blocks are given by 
The three blocks must remain in contact as they move, so they will each have the same velocity and acceleration regardless of their different masses. So, 
Example Question #1 : Displacement, Velocity, And Acceleration
A man walks two kilometers north and then two kilometers west. What is his displacement?
- 4 kilometers
- 4 kilometers northwest
- 2.8 kilometers northwest
- 8 kilometers northwest
- none of these
3
5
2
1
4
3
Choice 3 is correct. Recall that physics problems tell you where to begin and end. The only thing that matters in figuring displacement is the beginning point and end point. The man effectively walked along the hypotenuse of a right triangle whose sides measured 2 km each. Since a2 + b2 = c2, then 4 + 4 = c2, and the correct response is the square root of 8 with the direction of the displacement added for clarity.
Example Question #1 : Displacement, Velocity, And Acceleration
A boat sails straight north at 10 knots (10 nautical miles per hour) for ten hours. As it sails, a steady wind comes from the east at 5 knots. If the helmsman makes no correction for the wind, where will the boat be compared to its starting point?
- 50 nautical miles north of the starting point
- 150 nautical miles north of the starting point
- 112 nautical miles northeast of the starting point
- 112 nautical miles northwest of the starting point
- none of the above
5
4
3
1
2
4
Choice 4 is correct. In physics, it is often helpful to draw a diagram of the problem. In this case, the respondent would draw a vector 10 hours x 10 knots from south to north (usually going towards the top of a sheet of paper) and a perpendicular vector 50 nautical miles long projecting from the arrowhead of the first vector to the left, or west. The hypotenuse of the right triangle so created is the actual path of a boat experiencing these forces. Without resorting to calculating the square root of the sum of (10,000 plus 2,500 nautical miles2), it is obvious that choice 4 is the only reasonable one.
Example Question #2 : Displacement, Velocity, And Acceleration
A body travels 150km north, and then 500km east. Its total displacement is __________.
522km
350km
574km
650km
522km
To find total displacement, find the vector sum of the northern and eastern travel using the Pythagorean theorem.
Note that displacement differs from total distance traveled (which would be 650km).
Example Question #3 : Displacement, Velocity, And Acceleration
A body moves from position X at a constant velocity, v1, for two seconds, remains at rest for three seconds, and then returns to the original position X at a constant velocity v2 after four seconds. Which of the following represents the velocity of v2?
Since it takes the body twice the time to cover the same distance, the magnitude of v2 is half of v1. Also note that the direction of the body has reversed (velocity is a vector quantity), and so v2 must be negative, with regard to v1.
v = d/t
v1 = d/2
v2 = -d/4
v2 = (-1/2)v1
Example Question #4 : Displacement, Velocity, And Acceleration
A graph is made of the following motion by plotting time on the x-axis and velocity on the y-axis. An object accelerates uniformly between for three seconds, and then steadily increases the acceleration for the next three seconds. It remains at a constant velocity for the next two seconds. Which of the following is not true?
The slope is constant between seconds 3 and 6
The area under the curve is equal to displacement
The slope is zero between seconds 6 and 8
The slope is constant between seconds 1 and 3
The slope is constant between seconds 3 and 6
It is stated that between seconds 3 and 6 the object's acceleration increases. On a velocity vs. time graph, this would translate into a nonlinear curve.
Between seconds 1 and 3 the acceleration is constant, and would result in a linear velocity-time relationship. When the object travels at a constant velocity, the acceleration, which correlates to the slope, is zero.
Example Question #3 : Displacement, Velocity, And Acceleration
For a projectile moving in a parabolic path on Earth, which of the following is true? (Ignore wind resistance.)
The net force is tangent to the path of the projectile at any given time
The net force on the object is zero
The acceleration of the object is constant
The acceleration of the object is zero
The acceleration of the object is constant
Acceleration is equal to the acceleration due to gravity (about 10 m/s2) and is constant while the projectile is in the air. The force on the object is given by the product of its mass and gravitational acceleration, and is also constant.
Example Question #11 : General Principles
A particle is traveling to the right with decreasing speed. Which of the following shows the direction of acceleration?
Since the particle is decelerating the acceleration will be in the opposite direction of the movement. The particle is moving to the right, therefore its acceleration must be to the left.
Example Question #16 : General Principles
A man is walking through a forest. He walks north for 100m. He then turns left at an angle of 120o and walks for another 50m.
What is the man's total displacement?
This question requires us to find the end position relative to the starting position. As a result, 150m is not the correct answer; this would be the distance, not the displacement.
The first portion involves writing down that the person moves north 100m. At this point in time, his distance on the y-axis is +100m. Next, we have to see how the person's x-axis and y-axis distances change after turning left 120o, and walking 50m.
For the x-axis, we use the equation based on a right triangle. By turning 120o, the man is walking at an angle of 30o to the x-axis.
For the y-axis, we use the equation 
Now that we have the component vectors, we can use the pythagorean theorem to determine the total displacement of the man.
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