PHYS Straighterline
A binary star system consists of two identical stars moving in circular orbits around the system's center of mass (see the diagram). The mass of each star is M and the radius of the orbit is R. Which expression correctly gives the orbital speed for one of the stars?
(GM/4R)1/2
An automobile of mass 900 kg is moving at a speed of 12.5 m/s when it encounters a hill. At the bottom of the hill the car speed increases to 14.6 m/s. If the elevation of the hill is 15.3 m, how much work did the brakes do while going down the hill?
-1.09x105 J
A spaceship is in space and currently at rest. The directive is given to accelerate from rest to a speed of 2.90 × 103 m / s. If the fuel budgeted for this action is 400 kg, which of the following is velocity of the exhaust gas required if the ship mass is 7.38 × 103 kg?
-5.5 × 104 [m / s]
A stunt man is sliding down the side of a mountain when he manages to catch a tree with a wristwatch winch, which supplies a constant tension, T. Neglecting air friction, if the mountain slope is inclined at an angle θ, what is the acceleration of the stuntman?
-T / m + g sin θ
This diagram illustrates a water molecule (H2O). The oxygen atom has a mass of roughly 16 units, and the hydrogen atoms each have a mass of roughly 1 unit. The distance between the oxygen and hydrogen nuclei is 0.96 angstroms (an angstrom, denoted Å, is equal to 10−10 m). If the oxygen atom is located at y = 0, where is the vertical position of the center of mass of the molecule? Assume that hydrogen atoms lie towards positive y.
0.063 Å
In a game of marbles, a 60 g marble is rolling at 8.00 cm / s when it collides with a stationary marble. the 60 g marble takes off at a 27° angle at a reduced speed of 4.89 cm / s. The second marble moves at a rate of 3.21 cm / s at a 31.7° angle. Which of the following is the mass of the second marble?
0.0800 kg
A car travels with a speed of 3.5 m / s, and then accelerates to 5.5 m / s in 4 s. Which of the following is the average acceleration of the car?
0.5 m / s2
A 200 g plastic ball is at rest on a frictionless incline 0.658 m above the surface of a table. The ball then rolls down the incline and across the table, coming to rest after a distance of 2.45 m. Which of the following the average friction on the ball while rolling across the table.
0.527 N
An empty freight train car of mass 10,000 kg is rolling along a level section of track at 2.00 m / s. It collides with a loaded car of weight 1.96 × 105 N, which is at rest. The cars couple upon collision. Which of the following is the speed of the train after the collision?
0.667 m / s
A squirrel knocks an acorn loose near the top of a tree. If an observer on the ground were sitting 4 m directly below the acorn, how much time does the observer have to move out of the way before getting hit on the head?
0.9 s
Two rocket ships are flying in opposite directions at high speeds over the Earth's surface. Relative to the ground, one travels at 0.63 c, while the other travels at 0.91 c. How fast does one ship move relative to the other?
0.98 c
Laura is listening to a record spinning at 45 rpm (revolutions per minute). When she switches the speed selector on the record player to 33 rpm, it takes 2.7 seconds for the record player to change to the new speed. How many revolutions does the record make during this time? Assume that the angular acceleration of the record is constant.
1.8
Tricia's giant jack-in-the-box, Jerry, has now come to life, and wants revenge on her. While Tricia is away, Jerry devises a hydraulic press under Tricia's bed. The press allows Jerry to apply 20 times the force on Tricia's bed that he applies to the piston on his side. What is the ratio of the area of the piston on Jerry's side to the area of the piston under the bed?
1/20
A motorcycle is moving with a speed of 8.3 m / s when it begins to brake and slow down at a constant rate. If the acceleration is 3.1 m / s2, how much further will the motorcycle travel before it comes to a complete stop?
11 m
A new high-speed plane is flying horizontally at a speed of 0.75 c (this is not at all realistic). In the reference frame of the ground, the plane flies 1260 m above the ground. How high off the ground does the plane fly in its own reference frame?
1260 m
A 1,450 kg car moves with a speed of 25.0 m / s when it collides with a stationary car having a mass of 1,550 kg. The two vehicles lock bumpers on impact. The two cars then collide with a stationary third car of mass 1,250 kg. During this second impact, the third vehicle becomes attached to the second but the first car is breaks free and moves at 0.125 m / s in the opposite direction. Which of the following is the final velocity of the second and third cars after the final collision?
13.01 m / s
How fast must a baseball move as it leaves your hand if it reaches a maximum height of 15.0 m above the point where it left your hand?
17.1 m / s
When an asteriod that is headed directly for Earth is a distance of 8 Earth radii from Earth's center, it has a speed of 15 km / s. What is the speed of the asteroid when it collides with the Earth? Ignore any frictional effects of the atmosphere. The mass of the Earth is 5.98 × 1024 kg and the Earth's radius is 6.37 × 106 m.
18.3 km / s
Which of the following is the gravitational force between the Earth and the Moon? The Earth's mass is 6x10 24 kg, the moon's mass is 7.4 x 10 22 kg, and the distance between the centers of mass is 3.8 x 10 8 m.
2.1 x 10 20 N
Your cat chases a spider across the floor. Its position is a function of time is r + (1.2m/s)ti + (0.7m + (0.5m/s2)t2)j, where the origin is the southwest corner of the floor. Find the average speed of the cat between t = 0.0s and t = 4.0s
2.3 m/s
A freight train is traveling at a speed so that the angular velocity of its wheels is 38 rad / s. The engineer decides to accelerate the train to a speed 1.5 times faster than before. If the acceleration of the train corresponds to an angular acceleration of 0.80 rad / s2, how long does it take for the train to reach its new speed?
24 s
Tom and Joe are trying to fly a new style of kite that they have invented. Both of them are holding strings attached to the kite. The tension in each string is 126 N. The angle between the strings is 36°. Unfortunately, the kite will not rise in the air, and the strings held by Tom and Joe are essentially parallel to the ground. Tom and Joe have run a distance of 100 m trying to get the kite to fly. How much work have they done on the kite?
24,000 N • m
King Kong is holding a woman on top of a skyscraper when she suddenly slips out of his hand. How tall is the building if Superman has a minimum time of 2.30 s to catch the woman before she hits the ground?
25.9 m
A car is decelerating from 60 mph to 0 mph in 122 ft. If the tires have a diameter of 18 in., how many revolutions do the wheels make during the deceleration?
25.9 revolutions
Consider a sphere with a radius of 4.0830 m. What is its volume?
285.12 m 3
An experimental new ride at an amusement park begins by spinning patrons about a circle of radius R with constant speed v. At some point during the ride the speed doubles and the spokes extend, doubling the radius. After this occurs, what is the acceleration of the patrons in terms of the original acceleration, a ?
2a
How many significant figures are in the quantity 9.86 m/s 2?
3
A pendulum bob has mass of 0.750 kg and is on a pendulum arm of length 1.00 m. The pendulum is pulled back so that the arm makes an angle of 60.0° from the vertical and is then released. Which of the following is the speed of the mass when it reaches its lowest point?
3.13 m/s
Using Kepler's third law of planetary motion, how many times larger is the average radius of Neptune's orbit if it takes 164 Earth-years to orbit the Sun? Approximate each orbit as being circular.
30 times larger
A train is on an incline and has a mass of 2.36 × 103 kg. It initially coasts at 27.8 m/s. Which of the following is the speed of the train at position B. Assume no additional assistance from the engine.
34.2 m/s
A projectile is launched from a height of 250 m with initial horizontal velocity of 50 m/s. What is the horizontal range of the projectile?
357 m
Using the conversion factor between kilograms and pounds, 1 kg = 2.205 lb, calculate how many pounds are in 2.00 kg.
4.41 lb
An amusement park game consists of throwing a quarter into a small bowl. If you win, you get to take home a giant purple stuffed elephant. The dish is on a shelf that is 0.4 m above the point where the quarter leaves your hand. The horizontal distance between the bowl and the place where the quarter leaves your hand is 1.8 m. Ignoring air drag, if you toss the quarter at an angle of 60°, what initial velocity is needed to bring home the giant purple stuffed elephant?
4.8 m / s
If the cross product of a vector of length 5 and a vector of length 3 results in a vector of length 10, what is the angle between them?
42°
A meterstick is moving at a speed of 0.73c relative to you. In its own frame, the meterstick is tilted at an angle of 45 degrees. At what angle is it titled in your frame?
45 degrees
When viewed from above, a particular car has an area A1. Each of its four tires holds a pressure PT and contacts the ground with an area of A2. If atmospheric pressure is Patm, which of the following is the correct expression for the weight of the car?
4PTA2
If the x-component of a vector is 3 and the y-component is 4, what is the magnitude of the vector?
5
Consider a mass of 85kg lying on the ground. The coefficient of static friction between them is us = 0.65. What is the minimum force you need to apply in order to slide the mass?
541 N
You are rollerblading along the strand in Venice Beach, CA. You start at Muscle Beach at a speed of 8 km / hr. After skating 2.3 km you hit a pebble and a wheel falls off your skate. Luckily you were going slowly when it happened so you don't fall down. You take off your skates and walk 10 minutes to the rollerblade repair shop on the strand, which is 0.8 km away. Assuming the strand is perfectly straight, what is your average velocity?
6.7 km / hr
You are going for a bike ride. You ride down a straight road at a speed of 9.0 mi / hr. Just as you pass the point which is 3.6 miles from your starting point, you develop a flat tire. You get off you bike and walk it to a bike shop 0.5 mile further down the road. The walk to the bike shop takes 12 minutes. What was your average velocity for the entire trip?
6.8 mi / hr
Calculate x=vt+1/2at2, where v = 0.227 m/s. t = 11.1s, and a = 9.80 m/s2.
606 m
Suppose a parachutist with a mass of 67 kg jumps from an airplane. A few seconds after the person opens the parachute she measures her velocity—she is falling down at constant speed of 15 m / s. What is the force of air drag on her parachute?
656.6 N
The radius of the Moon is known to be 1.7 × 106 m. Astronauts who walked on the Moon measured the time it takes an object to fall 1 m on the Moon to be about 1.1 s. Using this information, which of the following is the mass of the Moon?
7.1 × 10 22 kg
NASA wants to launch a new satellite that will remain in a circular orbit 300 km above the surface of the Earth. Determine the orbital speed necessary for the satellite to remain in this orbit if the mass of the Earth is 5.97 × 1024 kg and its radius is 6.38 × 106 meters.
7720 m / s
Kylie throws Kyra a kiwi. The kiwi leaves Kylie's hand at a height of 1.3 m from the ground and Kyra grabs it out of the air at a height of 1.6 m. Kylie throws the kiwi at an angle of 33° relative to the horizontal. The kiwi is in the air for 1.1 s. How far apart are Kylie and Kyra standing? (Assume there is no drag force that no wind is blowing.)
9.6 m
Consider a spring that is stretched from its equilibrium position x0, where x0 = 0, to a position x, where x is positive. Which of the following describes why the work done by a spring is negative?
All of the choices are correct.
Which of the following statements is true for any completely enclosed ideal fluid?
Any change in pressure is transmitted equally to all points in the fluid.
Given the vector A as shown in the figure, select the choice that gives the vector's correct description in component form.
Ax = Acos0 Ay = Asin0
Given the vectors A = 6i + 3j and B = i + 9j, find their scalar product AxB.
AxB=33
Cats have amazing control over their bodies. If you hold a cat upside down a moderate height off the floor and drop it, it manages to right itself in midair and land on its feet. Isn't this a violation of the conservation of angular momentum? After all, the cat starts upside down, and then it somehow rotates until it is right-side up. Which of the following is the most plausible explanation for this phenomenon?
By manipulating its body, a cat can control the moment of inertia of different parts of its body in such a way that it can reorient itself in midair despite the fact that its angular momentum is zero the whole time.
The gravitational force between two objects has a magnitude of F. If both masses were doubled and the distance between them doubled, the new force would have which of the following magnitudes?
F
Car 1 of mass 700 kg is slowly moving along at 0.500 m / s when it is hit from behind by car 2 speeding along at 15.0 m / s. After collision, car 1 has a new speed of 8.00 m / s in the same direction. Which of the following is the force with which car 2 must have struck car 1, if the collision lasted for 0.932 s? Also, knowing that conservation of momentum applies to the situation, what is car 2's speed after the collision (v2 f ) if it has a mass of 850 kg?
F = 5.63 × 103 N v2 f = 8.82 m / s
Imagine that you push down on an object that is sitting on a frictionless table. Which of the following diagrams includes all the forces acting on the object?
F W down, N up
Which of the following is a form of Hooke's law, where Fs is a spring force?
Fs = -kx
A 0.500 kg steel ball is dropped from a height of 4.00 m onto a horizontal steel slab. The collision appears elastic in that the ball rebounds to its original height. If the collision lasts for 2.00 × 10−3 s, which of the following is the impulse imparted to the ball and the average force applied to the ball during the collision?
I = 8.85 kg•m / s F = 4.43 × 103 N
Which of the following is the general definition of impulse ?
I = squiqqle E Fdt
This hourglass-shaped object is hung from a pivot point (round dot). Its center of gravity is marked by a cross. If the object is free to rotate, what does it do?
It does not move.
Which of the following is not a unit of work?
J⋅m
How can you calculate the magnitude of a vector using scalar products?
Multiply it by itself and take the square root.
A dolphin trailing one of the Navy's aircraft carriers decides swim underneath the carrier. Does the presence of the ship affect the pressure changes the dolphin feels as it dives?
No, the pressure remains the same as when the ship wasn't there.
An observer O notes a particle moving to the right with velocity v. Another observer O ′ is moving with speed v relative to O along the direction of the motion of the particle. Which of the following is the value of the particle's mass as measured by O and O ′?
O measures m and O' measures m0
Where does the concept of moment of inertia come from?
Rotational kinetic energy
Why does an ice skater's angular velocity increase when she pulls in her arms during a spin?
She reduces her moment of inertia.
Which of the following statements concerning friction between the surfaces of two objects is correct?
The force of friction mostly depends on the nature of the two surfaces.
Which of the following statements concerning friction is incorrect?
The force of static friction ( fs ) between parallel surfaces in contact is given by: fs = μsN.
If two objects with the same radius, one with I1 = I and the other with I2 = 2I, both roll down an incline, which would reach the ground first?
The object with I1 = I.
Scientists are planning to put Ruffs the dog on the first spaceship capable of traveling at speeds near the speed of light. In the interest of saving space, the ship designers have made the cabin of the ship very small, so that Ruffs can barely fit inside. The dog will still be comfortable, they reason, because he will be Lorentz contracted during the trip. What is the best response to this reasoning?
The reasoning is not sound, because Ruffs will be Lorentz contracted relative to the Earth, but not relative to the ship
When turning around a circle, a car is subject to a continuous force, but its speed does not necessarily change. Why is this true?
The speed is not changing, but the direction is.
Which of the following statements concerning an object in free fall through the atmosphere is incorrect?
The speed of a falling object increases due to the frictional force of air drag.
How are seconds defined?
They are based on the time it take cesium atoms to vibrate.
Which is not a reason why measurements are important?
They give us an absolute analysis of the world around us.
As shown, a crate of oranges and a crate of apples, each with a different mass, are attached by a rope (with tension Toa). A second rope (To ) is attached to the crate of oranges, and the entire system is pulled with a constant acceleration a by this rope. Which of the following is true of the tensions?
Toa > To
Suppose you weigh an object and the reading you get from the scale is 0.0070 kg. How many significant digits does your measurement have?
Two
Which of the following is not a unit of power?
Watt / second
A mass m is dropped from rest to the ground from a height h. Which of the following is correct?
When it strikes the ground the speed of the mass is independent of m.
When designing elevators, it is important to consider the maximum tension a cable will support. Which of the following causes a maximum tension?
accelerating upward
Which of the following objects has the greatest kinetic energy?
an object of mass 2m and speed 3v
The derivation of Bernoulli's equation relies on _______________.
conservation of energy
Which of the following is involved in uniform circular motion?
constant angular velocity
Which of the following correctly shows the location of the center of mass of this system?
d - near bottom
In Newtonian physics, kinetic energy equals ½ mv 2. Which of the following is the relativistic definition of kinetic energy?
d) m0c2 - m0c2
A vector is quantity that requires both magnitude and ________.
direction
A power company charges its customers for electricity based upon which one of the following?
energy
Consider two objects sliding down an incline without rolling. If the objects don't have the same mass, the heavier object will accelerate at a faster rate than the lighter one.
false
Evaluate the following statement as true or false. Kepler's first law of planetary motion states that the Sun is at the center of a planet's elliptical orbit.
false
Bernoulli's equation does not include the effects of______________.
friction
A small mass is placed on a turntable that is rotating at 45 rpm. The centripetal acceleration is ____________.
greater when the mass is farther from the center of the circle
A force is applied to an object as shown. What is the direction of the torque vector?
into the screen
You are sparring in karate class. Your opponent, standing directly in front of you, throws a punch straight into your chest. What stance will best allow you to take this punch without losing your balance?
left forward
Which of the following is not an example of a vector?
mass
Which of the following is not a vector quantity?
power
A point mass m is hung on an ideal, massless rod of length z. A torque of magnitude r is applied to the system about P, displacing it as shown. What is the horizontal displacement L of the mass from vertical?
r/mg
The integral (squiggle)dt is called the angular impulse. It is equal to
the change in angular momentum
Two inertial observers are moving with relative speed v. An observer, O, measures the speed of an object in her reference frame to be u and notes O's speed to be v. What is the speed of the object in the prime inertial frame according to O ?
u = u-v/ (1-uv/c2)
The position of an object along the x-axis is described by the formula x = 3t 2 − 2t. Which of the following are the correct formulas for the velocity and acceleration of the object?
v = 6t − 2, a = 6
A truck weighing 1000 N moves at 5.89 m / s when it has an elastic collision with another vehicle. The second vehicle, weighing 981 N, was stationary but free to move. Which of the following is the final velocity of the first vehicle after the collision?
v1 f = 0.0565 m / s
A truck that weighs 1000 N moves at 5.89 m / s when it hits another vehicle in an elastic collision. The second vehicle, weighing 981 N, was stationary but free to move. Find the final velocity of the second vehicle after the collision.
v2 f = 5.95 m / s
A 309 g glass rolls down an incline and onto a horizontal platform where it hits a beverage can that is laying at rest on its side. The top of the incline is 11.0 cm above the horizontal platform. The beverage can is initially at rest and weighs 7.35 N. Which of following is the final velocity of the glass?
−0.612 m / s
Two children are playing catch in a passenger train. An observer on the ground measures that the train is traveling at 70 mph. As the train passes the observer, he measures that the ball is thrown with half of the speed as the passenger train. What velocity do the children measure for the ball? (Assume the positive direction is the direction in which the train is moving.)
−35 mph
A boat pulls a water skier who weighs 127 lbs at a constant speed. The tension in the ski rope is 125 N. The skier makes a run that is 0.7 km down a long straight river. What is the work done by the water skier on the boat?
−8.75 × 104 N • m
