Physics Final Conceptual Questions
Which of the following has three significant figures? A) 305.0 cm B) 0.0500 mm C) 1.00081 kg D) 8.060 × 1011 m2
0.0500
A 70-kg astronaut is space-walking outside the space capsule and is stationary when the tether line unfastens. As a means of returning to the capsule he throws his 2.0-kg space hammer at a speed of 14 m/s away from the capsule. At what speed does the astronaut move toward the capsule?
0.40 m/s
A ball of mass 0.10 kg is dropped from a height of 12 m. Its momentum when it strikes the ground is
1.5 kg m/s
A 0.060-kg tennis ball, initially moving at a speed of 12 m/s, is struck by a racket causing it to rebound in the opposite direction at a speed of 18 m/s. What is the change in momentum of the ball?
1.8 kg∙m/s
A ball is thrown with a velocity of 20 m/s at an angle of 60° above the horizontal. What is the horizontal component of its instantaneous velocity at the exact top of its trajectory?
10 m/s
An elevator that weighs 1000 N goes from rest to 3 m/s upward in a time of two seconds. During this time, what is the tension in the cable?
1150 N
Select the smallest value. A) 15 × 10-3 B) 0.15 × 100 C) 0.00015 × 103 D) 0.00000015 × 106
15 * 10^-3
An object is lifted vertically 2.0 m and held there. If the object weighs 90 N, how much work was done in lifting it?
180 J
The resultant of two vectors is the smallest when the angle between them is
180°
Express the number 0.02 days using a prefix
2 centi days
An object moves 15.0 m north and then 11.0 m south. Find both the distance traveled and the magnitude of the displacement vector.
26.0m and 4.0m
An airplane increases its speed from 100 m/s to 160 m/s, at the average rate of 15 m/s2. How much time does it take for the complete increase in speed?
4 seconds
Two vectors, of magnitudes 20 and 50, are added. Which one of the following is a possible answer for the magnitude of the resultant?
40
A friend is riding on the back of a truck that is moving away from you at 20 mph. After the truck has passed you, your friend throws a ball toward you at 60 mph, relative to her/him. What is the speed of the ball relative to you?
40 mph
A person of weight 600 N stands on a scale in the elevator. What will the scale be reading when the elevator is accelerating downward at 3.00 m/s2?
416 N
What is the percent uncertainty in the measurement 2.58 ± 0.15 cm?
5.8% (Equation: .15 * 100/2.58)
Two identical 1500-kg cars are moving perpendicular to each other. One moves with a speed of 25 m/s due north and the other moves at 15 m/s due east. What is the total momentum of the system?
6.0 × 104 kg∙m/s at 59° N of E
What is the sum of 2.67 + 1.976 + 2.1?
6.7
A ball is thrown at an original speed of 8.0 m/s at an angle of 60° above the horizontal. What is the speed of the ball when it returns to the same horizontal level?
8.0 m/s
A ball is thrown with a velocity of 20 m/s at an angle of 60° above the horizontal. What is the horizontal component of its instantaneous velocity at the exact top of its trajectory?
9.8 m/s^2
Which of the following is an accurate statement? A) A vector cannot have zero magnitude if one of its components is not zero. B) The magnitude of a vector can be less than the magnitude of one of its components. C) If the magnitude of vector A is less than the magnitude of vector B, then the x-component of A is less than the x-component of B. D) The magnitude of a vector can be positive or negative.
A vector cannot have zero magnitude if one of its components is not zero.
A 4.0-kg mass is moving with speed 2.0 m/s. A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater distance before stopping?
Both travel the same distance
What type of acceleration does an object moving with constant speed in a circular path experience?
Centripetal acceleration
A freight car moves along a frictionless level railroad track at constant speed. The car is open on top. A large load of coal is suddenly dumped into the car. What happens to the velocity of the car?
Decreases
In the following figure, student A has a mass of 75 kg and student B has a mass of 57 kg. They sit in identical office chairs facing each other. Student A places his feet on the knees of student B, as show. Student A then suddenly pushes outward with his feet, causing both chairs to move During the push, and while the students are still touching each other,
Each student exerts the same amount of force on the other
You slam on the brakes of your car in a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skidded, under the same conditions?
Four times as far
The area under the curve on a Force versus time (F vs. t) graph represents
Impulse
If the net work done on an object is positive, then the object's kinetic energy
Increases
Suppose a skydiver jumps from a high-flying plane. What is her acceleration when she reaches terminal velocity?
It is approximately 9.8 m/s^2 downward
Suppose a can, after an initial kick, moves up along a smooth hill of ice. Make a statement concerning its acceleration.
It will have the same acceleration both uphill and downhill
Suppose a ball is thrown straight up. Make a statement about the velocity and the acceleration when the ball reaches the highest point.
Its velocity is zero and its acceleration is not zero.
A ball falls from the top of a building, through the air (air friction is present), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the potential energy (U) at the top of the building?
K is less than U
The metric prefix for one one-thousandth is
Milli
When a cannon fires a cannonball, the cannon will recoil backward because the
Momentum of the cannonball and the cannon is conserved
Does the centripetal force acting on an object do work on the object?
No, because the object has constant speed
When is the average velocity of an object equal to the instantaneous velocity?
Only when the velocity is at constant
Angular velocity is expressed in units of
Radians per second
Ignoring air resistance, the horizontal component of a projectile's velocity
Remains constant
If you push twice as hard against a stationary brick wall, the amount of work you do
Remains constant at 0
A useful method of expressing very small or very large numbers is
Scientific Notation
The base SI unit of time is
Second
Four students measure the mass of an object, each using a different scale. They record their results as follows: Student A B C D Mass (g ) 49.06 49 50 49.2
Student A
A rubber ball and a lump of putty have equal mass. They are thrown with equal speed against a wall. The ball bounces back with nearly the same speed with which it hit. The putty sticks to the wall. Which objects experiences the greater momentum change?
The ball
A boy and a girl are riding a merry-go-round which is turning at a constant rate. The boy is near the outer edge, while the girl is closer to the center. Who has the greater centripetal acceleration?
The boy
Suppose that a car traveling to the West (-x direction) begins to slow down as it approaches a traffic light. Make a statement concerning its acceleration.
The car is slowing down thus the acceleration is negative.
If the acceleration vector of an object is directed anti-parallel to the velocity vector,
The object is slowing down
Two equal forces are applied to a door. The first force is applied at the midpoint of the door; the second force is applied at the doorknob. Both forces are applied perpendicular to the door. Which force exerts the greater torque?
The second at the door knob
A stone is thrown horizontally from the top of a tower at the same instant a ball is dropped vertically. Neglecting air resistance, which object is traveling faster when it hits the level ground below?
The stone
A 3.0-kg object moves to the right at 4.0 m/s. It collides head-on with a 6.0-kg object moving to the left at 2.0 m/s. Which statement is correct?
The total momentum both before and after the collision is zero.
A truck weighs twice as much as a car, and is moving at twice the speed of the car. Which statement is true about the truck's kinetic energy compared to that of the car?
The truck has 8 times the kinetic energy of the car
A brick is dropped from the top of a building. A second brick is thrown straight down from the same building. They are released at the same time. Neglect air resistance. Compare the accelerations of the two bricks.
The two bricks accelerate at the same rate.
A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the magnitude of the average collision force is correct?
They experience the same average force.
A Ping-Pong ball moving east at a speed of 4 m/s, collides with a stationary bowling ball. The Ping-Pong ball bounces back to the west, and the bowling ball moves very slowly to the east. Which object experiences the greater magnitude impulse during the collision?
They have the same impulse
A stone is thrown horizontally from the top of a tower at the same instant a ball is dropped vertically. Neglecting air resistance, which object will land first on the level ground below?
They will land at the same time
A car goes around a curve of radius r at a constant speed v. What is the direction of the net force on the car?
Toward the curves center
Objects A and B both start at rest. They both accelerate at the same rate. However, object A accelerates for twice the time as object B. What is the final speed of object A compared to that of object B?
Twice as fast
The number of significant figures in 0.01500 is
Two
The area under the curve, on a Force versus position (F vs. x) graph, represents
Work
Is it possible for an object moving with a constant speed to accelerate? Explain.
Yes, although the speed is constant, the direction of the velocity can be changing.
Can an object's velocity change direction when its acceleration is constant?
Yes. Throwing a rock up would be an example.
If you walk 5.0 m horizontally forward at a constant velocity carrying a 10-N object, the amount of work you do is
Zero
Two metal balls are the same size, but one weighs twice as much as the other. The two balls roll off a horizontal table with the same speed. In this situation,
both balls hit the floor at approximately the same horizontal distance from the base of the table
When is kinetic energy conserved?
elastic collisions
When an object experiences uniform circular motion, the direction of the acceleration is
is directed toward the center of the circular path.
A stone dropped from the roof of a single-story building to the surface of the Earth
speeds up because of an almost constant force of gravity acting upon it
After the car reaches the constant cruising speed at which the driver wishes to push the truck,
the amount of force with which the car pushes on the truck is equal to that with which the truck pushes back on the car;
Use the statement and figure below to answer Questions 3 and 4. A large truck breaks down on the road and receives a push back into town from a small, compact car as shown in the given figure. 3. While the car, pushing the truck, is speeding up to get to cruising speed,
the amount of force with which the car pushes on the truck is equal to that with which the truck pushes back on the car;
A large truck collides head-on with a small compact car. During the collision
the truck exerts the same amount of force on the car as the car does on the truck