Physics Final Exam Multiple Choice
There identical balls are thrown off a tall building with the same speed but in different directions. Ball A is thrown in the horizontal direction; ball B starts out at 45∘45∘ above the horizontal; ball C begins its flight at 45∘45∘ below the horizontal.
All three balls have the same speed.
Adam drops a ball from rest from the top floor of a building at the same time Bob throws a ball horizontally from the same location. Which ball hits the level ground first? (Neglect any effects due to air resistance.)
hey both hit the ground at the same time.
A boy roller-skating at constant velocity hits a wall and bounces back at constant velocity, as shown in the figure below. The boy's change in momentum is
in the +x direction
When a net force is acting on an object, the object
is accelerating
Which are the correct units for strain?
none
A block of mass 𝑚m slides down a rough incline with constant speed. If a similar block that has a mass of 9𝑚9m were placed on the same incline with the same initial speed as the first block, it would
slide down at the same constant speed.
Two particles with the same mass of 13 kg13 kg are involved in a completely inelastic head‑on collision. Before the collision, both particles have the same speed of 4 m/s.4 m/s. Which statement describes the velocities of the particles after the collision?
Both particles have zero velocity.
A student stays at her initial position for a bit of time, then walks slowly in a straight line for a while, then stops to rest a while, and finally runs quickly back to her initial position along a straight line. Which of the following statements is true about the average speed and the magnitude of the average velocity of the student during her trip?
Her average speed is greater than the magnitude of her average velocity.
Explain the difference between average speed and average velocity.
The average speed, a scalar, is greater than or equal to the magnitude of the average velocity vector over the same time interval.
3 different blocks with different masses, what block has smallest net force acting on it
The block with the smallest mass
The gravitational force acts on all objects in proportion to their mass. Neglecting air resistance, why don't heavy objects fall faster than light ones?
The gravitational acceleration of a falling object is independent of the object's mass and is thus the same for all objects.
Every object in the universe with mass experiences an attractive gravitational force due to every other object with mass. Why don't you feel a pull from objects close to you?
The gravitational forces between people and ordinary objects are far too small for people to feel.
Suppose that a solid ball, a solid disk, and a hoop all have the same mass and the same radius. Each object is set rolling without slipping up an incline with the same initial linear (translational) speed. Which object goes farthest up the incline?
The hoop rolls the farthest.
A tetherball swings in a horizontal circle as shown. The acceleration of the ball depends on
The length of the string, the angle of the string, and the speed of the ball (NOT THE MASS OF THE BALL)
Riders on a Ferris wheel move at constant speed. As the rider moves from the bottom of the Ferris wheel to the top
The magnitude of the net force remains the same, but the magnitude of the normal force decreases
A box is pulled with a rope along a frictionless table, as shown in the figure below How does the magnitude of the normal force compare to the weight of the box?
The magnitude of the normal force is less than the weight of the box.
Consider a completely elastic head-on collision between two particles that have the same mass and the same speed. What are the velocities of the particles after the collision?
The magnitudes of the velocities are the same but the directions are reversed.
Which is larger, the Sun's pull on Earth or Earth's pull on the Sun?
They pull on each other equally.
Tom runs into a stationary elephant that is much more massive than he. Which statement is true about the magnitudes of their forces?
Toms force on the elephant is equal to the elephant's force on Tom
A block on a spring slides on a horizontal frictionless surface in simple harmonic motion, as shown. At which point is the velocity of the block positive and the acceleration negative? At which point is the spring potential energy 𝑈springUspring greatest?
V, S
Draw a position-time, velocity-time and acceleration-time graph that would best depict the following scenario? A man starts at the origin, walks back slowly and steadily for 6 seconds. Then he stands still for 6 seconds, then walks forward steadily about twice as fast for 6 seconds.
Velocity: D, For position time graph: B
Why should the driver and passengers in a car wear seatbelts?
When a car moving forward at a constant speed vv comes to a sudden stop, passengers without seatbelts continue moving forward at speed v because of their inertia, according to Newton's first law.
What are the four false statements?
When the ball is pulled inward and the length of the string is shortened, the rotational kinetic energy remains constant due to conservation of energy, (C) but the angular momentum 𝐿L will not remain constant because there is an external force acting on the ball to pull it inward. (D) The moment of inertia 𝐼I remains constant and (E) the angular speed will remain the same throughout the process because the ball is rotating in the same plane throughout the motion.
Five balls are thrown off a cliff at the angles shown in the figure. Each has the same initial speed. (Neglect any effects due to air resistance.) Identify the ball that will have the STOWEST vertical component of final speed right before it hits the ground.
ball 3 horizontal
Four rods that obey Hooke's law are each put under tension. (a) A rod 50.0 cm50.0 cm long with cross-sectional area 1.00 mm21.00 mm2 and with a 200 N200 N force applied on each end. (b) A rod 25.0 cm25.0 cm long with cross-sectional area 1.00 mm21.00 mm2 and with a 200 N200 N force applied on each end. (c) A rod 20.0 cm20.0 cm long with cross-sectional area 2.00 mm22.00 mm2 and with a 100 N100 N force applied on each end.
c<a=b
In both cases shown below a hula hoop with mass M and radius R is spun with the same angular velocity about a vertical axis through its center. In Case 1 the plane of the hoop is parallel to the floor and in Case 2 it is perpendicular. In which case does the spinning hoop have the most kinetic energy?
case 1
The net force on a moving object suddenly becomes zero and remains zero. The object will
continue at constant velocity
An Escherichia coli (E. coli) bacterium propels itself slowly through water at a constant speed by means of long, thin structures called flagella. If the force exerted on the water by the flagella doubles, the velocity of the bacterium
doubles
A car moves along a straight, level road. As the car's velocity changes from 50 mph50 mph due south to 50 mph50 mph due north, the kinetic energy of the car
first decreases, then increases to its initial value.
Case A in the figure shows block 1 being accelerated across a frictionless table by a hanging 10 N10 N block (1.02 kg).(1.02 kg). In case B, the same block is accelerated by a steady 10 N tension in the string. Treat the masses of the strings and pulley as negligible, and the string as frictionless.
greater than its acceleration in case A
The figure shows three objects that are all made of the same material. The forces applied to the three objects all have the same magnitude.
(iii)>(i)=(ii)
Which of the graphs of the unspecified function of time 𝑓(𝑡)f(t) vs. 𝑡t shows the angular acceleration for the motion of the hollow cylinder?
A
Three identical balls are thrown off a tall building with the same speed but in different directions. Ball A is thrown in the horizontal direction; ball B starts out at20" above the horizontal; ball C begins its flight at20" below the horizontal. Which ball has the greatest speed just before it hits the ground? Ignore any effects due to air resistance.
All three balls have the same speed.
How do geostationary satellites remain stationary over one point on Earth?
By orbiting Earth in the equatorial plane with the same rotational direction and angular speed as Earth's spin.
A student stays at her initial position for a bit of time, then walks slowly in a straight line for a while, then stops to rest a while, and finally runs quickly back to her initial position along a straight line. Which of the position versus time plots best represents the student's trip?
C
A wire is stretched just to its breaking point by a force F. A longer wire made of the same material has the same diameter. The force that will stretch the longer wire to its breaking point is
equal to 𝐹
The figure graphs the 𝑥x‑component of the velocity of a car traveling in a straight line Over which intervals of time is the car slowing down? interval 1: From t=0 st=0 s to about t=1.3 st=1.3 s interval 2: From about t=1.3 st=1.3 s to t=3 st=3 s interval 3: From t=3 st=3 s to t=4 st=4 s interval 4: From t=4 st=4 s to t=5 st=5 s interval 5: From t=5 st=5 s to t=7 st=7 s interval 6: From t=7 st=7 s to about t=8.7 st=8.7 s interval 7: From about t=8.7 st=8.7 s to t=10 s
intervals 2 and 6 (anytime going towards zero)
Emmy the trapeze artist flies through the air with her arms and legs stretched out, tumbling hcad ovcr heels. As she rotates, she pulls her arms and legs close to her chest, as shown in the illustration. As Emmy pulls her arms antl legs in, how does her rotatiotral speed change?
it increases
How does the magnitude of the normal force exerted by the ramp on the block in the figure compare to the weight of the block? The normal force is
less than the weight of the block
. If x is in meters [m) and t is in seconds (s), what are the units of C in this equation: x = Ct^2/4
m/s^2
Sandra is on a rotating Ferris wheel. When Sandra is at the bottom of the Ferris wheel's rotation, how does the magnitude of the normal force N exerted on her by her seat compare to her weight mg ?
𝑁>𝑚𝑔
When throwing a ball straight up, which of the following are correct about the magnitudes of its velocity 𝑣v and its acceleration 𝑎a at the highest point in its path?
𝑣=0v=0 but 𝑎=9.80 m/s2
The figure shows position 𝑥x versus time 𝑡t graphs for four separate objects, all drawn on the same axes. Each object moves at a constant velocity from 𝑡=0 st=0 s to 𝑡=5 st=5 s . What is the correct ordering of the objects' velocities 𝑣𝑖vi, indexed 𝑖=i,ii,iii,ivi=i,ii,iii,iv , from the most negative to the most positive?
𝑣iv<𝑣i<𝑣ii<𝑣iii
Position vs Time Graph: at what point is object slowest?
where slope is 0
position versus time graph for a moving object: at what point is object moving the fastest
where slope is the steepest
How to figure out the accelerations of different masses
A = F/M
Replacing an object attached to a spring with an object having 1414 the original mass will change the frequency of oscillation of the system by a factor of
2
. A solid disk of mass M, radius & and initial angular velocity wo counterclockwise is dropped onto a similar disk with an initial angular velocity wo clocla¡¡ise. What is the angular velocity of the two disks after they are stuck together?
0
A satellite and the International Space Station have the same mass and are going around Earth in concentric orbits. The distance of the satellite from Earth's center is twice that of the International Space Station's distance. What is the ratio of the centripetal force acting on the satellite compared to that which is acting on the International Space Station?
0.25
What is the net force on a bathroom scale when a 75 kg75 kg person stands on it?
0N
You are given two solid cylinders (l = Yz mRz), which are (1) brass and (2) wood, and two rings (l = mR2), which are (3) brass and [4) wood; the radius R is the same for all, but brass has a higher mass m than wood. If all are released from the same starting line at the same time, the one(s) that reach[es) the bottom first are(is)
1 and 2
Examples of simple harmonic motion that can be observed in everyday life.
1. lightly bouncing on a trampoline when your feet do not leave the canvas 2. a pendulum in a grandfather clock 3. a child gently swinging on a playground swing at small angles
You are driving on the interstate in heavy traffic going 25 m/s. As you pass the accidentthat was holding you up on the side of the road, you are able to then accelerate atL.2 m/szfor 5 s. How far do you travel during these 5 seconds?
140m
Anne is working on a research project that involves the use of a centrifuge. Her samples must first experience an acceleration of 100g, but then the acceleration must increase by a factor of8. By how much willcthe rotation speed vt have to increase? Express your answer as a multiple of the initial rotation rate ui.
2.83 (wf = wi*sqrt(8))
A 50.0-crn-wide door is pushed open with a force of Ir=50.0 N at 25 degrees, as shown. Calculate the torque about an axis that passes through the hinges.
22.7
When tension is applied to a metal wire of length 𝐿, it stretches by Δ𝐿 If the same tension is applied to a metal wire of the same material with the same cross-sectional area but of length 2𝐿, by how much will it stretch?
2Δ𝐿
The escape speed from planet X is 𝑣.v. Planet Y has the same radius as planet X but is twice as dense. The escape speed from planet Y is
2√𝑣
A tennis player smashes a ball of mass 𝑚m horizontally at a vertical wall. The ball rebounds at the same speed 𝑣v with which it struck the wall. Has the momentum of the ball changed, and if so, by how much?
2𝑚𝑣
A small object is attached to a horizontal spring and set in simple harmonic motion with amplitude 𝐴A and period 𝑇T. How long does it take for the object to travel a total distance of 6𝐴6A?
3/2(𝑇)
A small object is attached to a horizontal spring, pushed to position 𝑥=−𝐴x=−A, and then released. The object undergoes simple harmonic motion with period 𝑇.T. How long does it take for the object to travel a total distance of 3𝐴3A? Now assume that the object is initially at 𝑥=0x=0 and given an initial velocity such that it oscillates with the same amplitude 𝐴.A. Relative to your previous answer, how much does the time to travel 3𝐴3A change under these new conditions
3/4 T, NO CHANGE
A361 kg box is pulled 7.00 m up a 30o frictionless, inclined plane by an external force of 4825 N that acts parallel to the plane. The net work done by the external force is
33800 N (4825x7)
Using the parallel-axis theorem, we calculated the moment of inertia for complicated contraptions such as a combination of rod, hoop and sphere. You used the theorem to derive an expression for the moment of inertia l for a solid, uniform sphere of mass M and radius r about an axis that is tangent to its surface. Which of the following is the correct expression for l when the axis is tangent to its surface?
7/5Mr^2
A pitching machine is programmed to pitch baseballs horizontally at a speed of 87 mph. The machine is mounted on a truck and aimed backward. As the truck drives away from a man at a speed of 55 mph, the machine shoots a ball towards him, what is the speed of the pitched ball relative to the truck
87 mph
Triangle problem from greatest to least
A,C,B
A fox locates its prey, usually a mouse, under the snow by the slight sounds that it makes. The fox then leaps straight into the air and burrows its nose into the snow when it lands, to catch its next meal. Which of the three pairs of velocity versus time 𝑣𝑦(𝑡)vy(t) and acceleration versus time 𝑎𝑦(𝑡)ay(t) graphs represent the free-fall motion of the fox? Assume the +y+y direction
B
Three objects of the same mass begin their motion at the same height. One object falls straight down, one slides down a low-friction inclined plane, and one swings in a circular arc on the end of a string. All three objects end at the same height.
Gravity does equal work on all three objects.
9. Consider the following three cases: Case 1: A person holds her arm at an angle of 30o above the horizontal (hand is higher than shoulder). Case 2: A person holds her arm straight out parallel to the ground. Case 3: A person holds her arm at an angle of 30" below the horizontal (hand is lower than shoulder). In which of the cases is the torque about the shoulder due to the weight of the arm the greatest?
Case 2
Which of the graphs of the unspecified function of time 𝑓(𝑡)f(t) vs. 𝑡t shows the angular velocity for the motion of the hollow cylinder?
E
A person is driving a car down a straight road. The instantaneous acceleration is constant and in the direction of the car's motion. What is the speed of the car?
Increasing
When constructing a free‑body diagram, why is it a good idea to choose a coordinate system so that the motion of an object is along one of the axes?
It eliminates the need to determine the vector components of the acceleration of the object.
A block of mass 𝑚m attached to a horizontally mounted spring with spring constant 𝑘k undergoes simple harmonic motion on a frictionless surface. How would the maximum speed of the block be affected if the spring constant was increased by a factor of 4 while holding the amplitude of oscillation constant?
It would increase by a factor of 2 (K is in a square root)
You need to push a heavy box across a rough floor, and you want to minimize the average force applied to the box during the time the box is being pushed. Which method of pushing results in the minimum average force being applied to the box? This would be the best method because the maximum coefficient of static friction is ________ the coefficient of kinetic friction. Therefore, the applied force required to ________ the box's motion is relatively small.
Keep pushing the box forward at a steady speed. greater than maintain
Which quantities are fundamental quantities?
Length and Time
Two ice skaters, Lilly and John, face each other while at rest, and then push against each other's hands. The mass of John is three times that of Lilly. How do their speeds compare after they push off?
Lilly's speed is three times John's speed.
Human skin is under tension like a rubber glove that has had air blown into it. Why does skin acquire wrinkles as people get older?
Many individual fibers in an older person's skin have exceeded their elastic limits.
The figure shows four situations in which a box slides to the right a distance 𝑑d across a frictionless floor as a result of applied forces, only one of which is shown in each case. The magnitudes of the forces shown are identical. Rank the four cases in order of the work done on the box by the force during the displacement. Consider both the magnitude and the sign of the work done in each case.
Most: A,C,B,D
Sandra is on a rotating Ferris wheel. When Sandra is at the bottom of the Ferris wheel'srotation, how does the magnitude of the normal force N exerted on her by her seat compare toher weight mg?
N>mg
A block having mass M slides on a frictionless surface and collides with a block of mass 2M, which is initially at rest. After the collision, the small block is at rest, and the larger block is moving to the right with speedVl2.
No
A cyclist rides around a flat, circular track at constant speed. Is the cyclist's acceleration vector zero?
No, because the direction of the cyclist's velocity vector changes constantly.
Choose the option that correctly answers and explains the question, "If the sum of the forces acting on an object equals zero, does this imply the object is at rest?"
No, because the sum of the forces equaling zero only implies that the object is not accelerating.
All valid equations in physics have consistent units. Are all equations that have consistent units valid?
No. An equation may have consistent units but still be numerically invalid.
Angular velocity increases from 3 radians/s to 5 radians/s during a time interval of 4 s. What is its angular acceleration during this time interval?
O.5 radians/sz
A fluid‑like substance called synovial fluid lubricates the surfaces where bones meet in joints, making the coefficient of static friction between bones very small. For simplicity, assume the surfaces in the knee are flat and horizontal. Why is the minimum force required for initiating movement of bones in a typical knee joint different for different people, in spite of the fact that their joints have the same coefficient of static friction
People weigh different amounts.
A block on a frictionless surface is attached to a horizontal spring and set in simple harmonic motion. The figure gives a top-down view of the system. When the spring is relaxed, the block is at position B, where the displacement 𝑥x from the equilibrium position is 00. Letting 𝐷D represent the maximum displacement, the extremes of the block's motion are at position A, where 𝑥=−𝐷x=−D, and at position C, where 𝑥=𝐷x=D.
Positions A and C
Which properties should an object, system, or process have in order for it to be a useful standard of measurement for a physical quantity such as length or time?
Precise and Reproducible
Which of the following choices explains why mechanical energy is always conserved in an ideal simple harmonic oscillator?
The restoring force acting on the oscillator obeys Hooke's law, making it a conservative force.
A horizontally oriented 2" × 4" pine stud is securely clamped at one end to an immovable object. A heavy weight hangs from the free end of the wood, causing it to bend. Which surface of the stud is under compression, and which surface is under tension?
The top surface is under tension and the bottom surface is under compression.
The car shown below is moving much faster than the heavier truck when they collide. Which of the choices below best describes the forces?
The truck exerts the same amount of force on the car as the car exerts on the truck.
James Bond leaps without a parachute from a burning airplane flying at 15,000 ft. Seconds later, his assistant, who was following behind in another plane, dives after him wearing her parachute and clinging to one for her hero. Is it possible for her to catch up with Bond and save him?
Yes, because Bond can orient himself horizontally and spread his limbs to increase drag, and his assistant can orient herself vertically and streamline her profile to reduce drag.
Select the option that best explains why conservation of energy alone is not sufficient to explain the motion of a Newton's cradle toy, such as the one shown in the figure. When two balls are raised and released together, conservation of energy is not sufficient to describe the subsequent the motion because it
allows for a single ball ejected on the opposite end to rise to twice the initial release height.
Starting from Newton's second law, explain how a collision that is free from external forces conserves momentum. In other words, explain how the momentum of the system remains constant with time. Newton's second law states that the acceleration of each object, which is proportional to each object's change in momentum, is proportional to the sum of the forces on the object. In the absence of external forces,
only the internal forces that the colliding objects exert on each other remain. Then, the sum of the internal forces is proportional to the change in momentum of the system. Applying Newton's third law, the internal forces sum to zero, which implies the change in momentum of the system is also zero.
You push two boxes along a straight line from one side of a room to the other. Each box begins and ends at rest. The contact surface and areas between the box and floor are the same for both, but one box is heavy and the other is light. Which of the following statements is correct?
same net work done on both boxes
ln the game of tetherball, a rope connects a ball to the top of a vertical pole, as shown in the figure. ln one case, a ball of mass m1 is the rope. ln the second case, a ball of mass m2 =2m attached to the rope. ln both cases, the speed of the ball is the sameWhat is the tension Tr in the rope with ball m1 compared to the tension T2 in the rope with ball m2, if the ropes make the same angle 0 with the vertical pole in both cases?
t1 = 0.5t2
A student in pushing a 50-kg box along a carpeted platform as shown. The block, however, remains at rest. The frictional force on the box will be bigger if
the magnitude of the pushing force is increased
A 50-kg student pushes on a 2-kg box that moves at a constant speed along a smooth surface, as shown. Which of the following corresponds to a Newton's third law force pair?
the push on the box by the student and the push on the student by the box
A person weighing w newtons stands on a scale in an elevator that is initially at rest. Theelevator accelerates upward to a constant speed, travels at that constant speed for someamount of time, and then slows to a stop. Which of the graphs below best represents thereading on the scale as a function of time?
upwards half circle, flat, downwards half circle
Which relationship is dimensionally consistent with a value for acceleration? In these equations, 𝑥x is distance, t is time, and v is speed.
v/t
A ball is thrown straight up. Which of the following is correct about the magnitudes of the ball's velocity (𝑣v) and acceleration (𝑎a) at the highest point in its trajectory? There is not enough information to determine the velocity (𝑣v) and acceleration (𝑎a).
v=0, but 𝑎=9.80 m/s2
When pushing a block where do you have max static friction
when the box is on the verge of slipping
