Physic Test Questions
A block of mass 5 kilograms lies on an inclined plan. the horizontal and vertical supports for the plane have lengths of 4 meters and 3 meters, respectively. The coefficient of friction between the plane and the block is 0.3. The magnitude of the force F necessary to pull the block up the plane with constant speed is most nearly
42 N
An 800-N box is pushed up an inclined plane. The plane is 4.0 m long and rises 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What was the magnitude of the average friction force on the box?
400 N
A force F is exerted by a broom handle on the head of the broom, which has a mass m. The handle is at an angle to the horizontal. The work done by the force on the head of the broom as it moves a distance d across a horizontal floor is
Fdcos0
An object is located inside a thin, uniform density spherical shell. At what locations would the object not be subject to a net gravitational force?
anywhere within the shell
A square piece of plywood on a horizontal tabletop is subjected to the two horizontal forces shown above right. Where should a third force of magnitude 5 newtons be applied to put the piece of plywood into equilibrium
on the top left corner
If you push twice as hard against a stationary brick wall, the amount of work you do
remains constant at zero
If the potential energy function is given by U(r)=(br^-3/2)+c, where b and c are constants, which of the following is an expression for the force on the particle?
(3b/2)r^-5/2
A red ball with a velocity of +3.0 m/s collides head-on with a yellow ball of equal mass moving with a velocity of -2.0 m/s. What is the velocity of the red ball after the collision?
-2.0 m/s
When a block slides a certain distance down an incline, the work done by gravity is 300 J. What is the work done by gravity if this block slides the same distance up the incline?
-300 J
A student holds one end of a string in a fixed position. A ball of mass 0.2 kg attached to the other end of the string moves in a horizontal circle of radius 0.5 m with a constant speed of 5 m/s. How much work is done on the ball by the string during each revolution?
0 J
A constant force =2Ni+3Nj acts on a 5 kilogram object as it moves in a straight line from the position 1=1mi+1mj to a position 2=4mi-1mj. Determine the work done by the force during this motion
0 Joules
Refer to Fig. 7-2. What is the amount of work done by the force F3 as the object moves up the inclined plane
0 Joules
The moons of Mars, Phobos and Deimos are very close to the planet compared to Earth's Moon. Their orbital radii are 9,378 km and 23,459 m respectively. What is the ratio of the period of revolution of Phobos to that of Diemos?
0.2528
A stock person at the local grocery store has the job of 1) picking up boxes of tomatoes form the stockroom floor, 2) accelerating to a comfortable speed, 3) carrying the boxes to the tomato display at constant speed, 4) decelerating to a stop, and 5) lowering the boxes slowly to the floor. During which of the five segments of the stock person's task is positive work being done to the boxes
1) and 2)
What is the period of a satellite circling Mars 100 km above the planet's surface? The mass of Mars is 6.42*10^23 kg, its radius is 3.40*106 m, and G=6.67*10^11 m^3/kg/s^2
1.75 hours
The gravitational acceleration on a planet's surface is 16.00m/s^2. What is the gravitational acceleration at distance of one planet diameter above the surface of the planet?
1.78m/s^2
For a particular nonlinear spring, the relationship between the magnitude of the applied force F and the resultant displacement x from equilibrium is given by the equation F=kx^2. What is the amount of work done by stretching the spring a distance x0?
1/3 kx0^3
When the friction-less system shown above is accelerated by an applied force of magnitude F, the tension in the spring between the blocks is
1/3F
A 1000 W electric motor lifts a 100 kg safe at constant velocity. The vertical distance through which the motor can raise the safe in 10 s is most nearly
10 m
A rock is dropped from the top of a 45-meter tower, and at the same time a ball is thrown from the top of the tower in a horizontal direction. Air resistance is negligible. The ball and the rock hit the level ground a distance of 30 meters apart. The horizontal velocity of the ball thrown was most nearly
10 meters/second
Refer to Fig. 7-2. what is the amount of work done by force F1 as the object moves up the inclinedplane
12 Joules
An object is dropped from rest from the top of a 400 meter cliff on Earth. If air resistance is negligible, what is the distance the object travels during the first 6 seconds of its fall
180 meters
Two .6 kilogram objects are connected by a thread that passes over a light, friction-less pulley, as shown above. the objects are initially held at rest. If a third object with a mass of .3 kilograms is added on top of one of the .6 kilogram objects as shown and the objects are released, the magnitude of the acceleration of the .3 kilogram object is most nearly
2 m/s^2
the position of a toy locomotive moving on a straight track along the x axis is given by the equation x=t^3-6t^2+9t, where x is in meters and t is in seconds. The net force on the locomotive is equal to zero when t is equal to
2 seconds
A stone, of mass m, is attached to a strong string and whirled in a vertical circle of radius r. At the exact top of the path the tension in the string is 3 times the stone's weight. The stone's speed at this point is given by
2 times the square root of gr
A ball is thrown upward. At a height of 10 meters above the ground, the ball has a potential energy of 50 joules (with the potential energy equal to zero at ground level) and is moving upward with a kinetic energy of 50 joules. Air friction is negligible. The maximum height reached by the ball is most nearly
20 m
Refer to Fig. 7.2. What is the amount of work done by force F2 as the object moves up the inclined plane
20.8 Joules
A 100 newton weight is suspended by two cords as shown in the figure above. The tension in t slanted cord is
200 newtons
When the frictionless system shown above is accelerated by an applied force of magnitude the tension in the string between the blocks is
2F
During a certain time interval, a constant force delivers an average power of 4 watts to an object. If the object has an average speed of 2 meters per second and the force acts in the direction of motion of the object, the magnitude of the force is
2N
A particle of mass m moves along a straight path with a speed v defined by the function v=bt^2+c, where b and c are constants and t is time. What is the magnitude F of the net force on the particle at t=t1
2mbt1
A target T lies flat on the ground 3 meters from the side of a building that is 10 meters tall, as shown above. A student rolls a ball off the horizontal roof of the building in the direction of the target. Air resistance is negligible. The horizontal speed with which the ball must leave the roof if it is to strike the target is most nearly
3 divided by the square root of 2 meters/second
Planet Z-34 has a mass equal to one-third that of Earth and a radius equal to one-third that of Earth. With g representing, as usual, the acceleration due to gravity on the surface of Earth, the acceleration due to gravity on the surface of Z-34 is
3 g
An object released from rest at time t=0 slides down a friction-less incline a distance of 1 meter during the first second. The distance traveled by the object during the time interval from t=1 second to t=2 seconds is
3 meters
The hydrogen atom consists of a proton of mass 1.67*10^27 kg and an orbiting electron of mass 9.11*10^31 kg. In one of its orbits, the electron is 5.3*10^11 m from the proton. What is the mutual attractive gravitational force between the electron and proton?
3.6*10^47 N
A target T lies flat on the ground 3 m from the side of a building that is 10 m tall. A student rolls a ball off the horizontal roof of the building in the direction of the target. Air resistance is negligible. The horizontal speed with which the ball must leave the roof if it is to strike the target is most nearly
3/the square root of 2 m/s
An object weighing 300 N is suspended by means of two cords. The tension in the horizontal cord is
300 N
A body moving in the positive x direction passes the origin at time t = 0. Between t = 0 and t = 1 second, the body has a constant speed of 24 meters per second. At t = 1 second, the body is given a constant acceleration of 6 meters per second squared in the negative x direction. The position x of the body at t = 11 seconds is
36 meters
A descending elevator of mass 1,000 kg is uniformly decelerated to rest over a distance of 8 m by a cable in which the tension is 11,000 N. The speed vi of the elevator at the beginning of the 8 m descent is most nearly
4 m/s
A 2.00*108 kg mass is located at x=100m, y=0.0m. A 5.00*108 kg mass is located at x=0.0m, y=200m. Determine the gravitational force on a 3.00kg mass located at x=0.0m, y=0.0m
4.00*10^6 Ni + 2.50*10^6Nj
A block of mass 5 kilograms lies on an inclined plane, as shown above. The horizontal and vertical supports for the plane have lengths of 4 meters and 3 meters, respectively. The coefficient of friction between the plane and the block is 0.3. The magnitude of the force F necessary to pull the block up the plane with constant speed is most nearly
42 newtons
A projectile is fired from the surface of the Earth with a speed of 200 meters per second at an angle of 30 degrees above the horizontal. If the ground is level, what is the maximum height reached by the projectile?
500 m
A projectile is fired from the surface of the Earth with a speed of 200 meters per second at an angle of 30 degrees above the horizontal. If the ground is level, what is the maximum height reached by the projectile
500 meters
in a game of pool, the white cue ball hits the #9 ball and is deflected at a 35 degree angle to the original line of motion. what is the angle of deflection below the original line of motion for the #9 ball?
55 degrees
The position of an object is given by the equation x=3.0t^2 + 1.5t + 4.5, where x is in meters and t is in seconds. What is the instantaneous acceleration of the object at t=3.0s?
6.0 m/s^2
To stretch a certain nonlinear spring by an amount x requires a force F given by F=40x-6x^2, where F is in newtons and x is in meters. What is the change in potential energy when the spring is stretched 2 meters from its equilibrium position?
64 J
Two blocks are pushed along a horizontal friction-less surface by a force of 20 newtons to the right, as shown above. The force that the 2 kilogram block exerts on the 3 kilogram block is
8 newtons to the left
A 500-kilogram sports car accelerates uniformly from rest, reaching a speed of 30 meters per second in 6 seconds. During the 6 seconds, the car has traveled a distance of
90 m
Three blocks of masses 3m, 2m, and m are connected to strings A, B, and C as shown above. The blocks are pulled along a rough surface by a force of magnitude F exerted by string C. The coefficient of friction between each block and the surface is the same. Which string must be the strongest in order not to break
C
If F1 is the magnitude of the force exerted by the Earth on a satellite in orbit about the Earth and F2 is the magnitude of the force exerted by the satellite on the Earth, then which of the following is true
F1 is equal to F2
Kepler's second law tells us that a planet sweeps out equal areas in equal times. If you compare the amount of area per time swept by Earth with the one of Jupiter, you would conclude
Jupiter sweeps a larger area per time because it has a much larger orbital path than Earth
Two blocks of masses M and m, with M>m, are connected by a light string. The string passes over a friction-less pulley of negligible mass so that the blocks hang vertically. The blocks are then released from rest. What is the acceleration of the block of mass M
M-m divided by M+m multiplied by g
The graph above shows the force of gravity on a small mass as a function of its distance R from the center of the Earth of radius Re, if the Earth is assumed to have a uniform density. The work done by the force of gravity when the small mass approaches Earth from far away and is placed into a circular orbit of radius R2 is best represented by the area under the curve between
R=R2 and R=infinity
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?
The small car and the truck experience the same average force
You need ot load a crate of mass m onto the bed of a truck. One possibility is to life the crate straight up over a height h, equal to height of the truck's bed. The work done in this case is W1. The other possibility is to slide the crate up the friction-less ramp of length L as shown in Fig. 8-1. In this case you perform work W2. What statement is true
W1=W2
A mass m moves on a curved path from point x to point y. Which of the following diagrams indicates a possible combination of the net force F on the mass, and the velocity v and acceleration a of the mass at the location shown
a and F are pointed east and v is pointed north east
The graph above shows velocity v versus time t for an object in linear motion. Which of the following is a possible graph of position x versus time t for this object
an upside down v
A ball initially moves horizontally with velocity vi, as shown above. It is then struck by a stick. After leaving the stick, the ball moves vertically with a velocity vf, which is smaller in magnitude than vi. Which of the following vectors best represents the direction of the average force that the stick exerts on the ball
arrow facing north west
Two identical balls are thrown from the top of a building with the same speed. Ball 1 is thrown horizontally, while ball 2 is thrown at an angle above the horizontal. Neglecting air resistance, which ball will have the greatest speed when hitting the ground below
both balls reach the ground with the same speed
Vectors v1 and v2 shown above have equal magnitudes. The vectors represent the velocities of an object at times t1 and t2 respectively. The average acceleration of the object between time t1 and t2 was
directed north of west
Which of the following pairs of graphs shows the distance traveled versus time and the speed versus time for an object uniformly accelerated from rest
distance has a positive upwards curve (like half a U) and speed has a positive linear line
Identical forces act for the same length of time on two different masses. The change in momentum of the smaller mass is
equal to the change in momentum of the larger mass
You ride on an elevator that is moving upward with constant speed while standing on a bathroom scale. The reading on the scale is
equal to your true weight, mg
Which of the graphs in Fig 7-1 illustrates Hooke's Law
graph b (negative linear line)
Which of the graphs in Fig. 7-1 represents a spring which gets less stiff the more it is stretched
graph d (half a u in the negative y)
List the four fundamental forces in nature
gravitational, electromagnetic, strong nuclear, weak nuclear
An object is thrown with velocity v from the edge of a cliff above level ground. Neglect air resistance. In order for the object to travel a maximum horizontal distance from the cliff before hitting the ground, the throw should be at an angle with respect to the horizontal of
greater than 45 degrees but less than 60 degrees above the horizontal
Because Earth's orbit is slightly elliptical, Earth actually gets closer to the Sun during part of the year. When Earth is closer to the Sun its orbital speed is
greater than when Earth is farthest away from the Sun
A spring-loaded gun can fire a projectile to a height h if it is fired straight up. If the same gun is pointed at an angle of 45 degrees from the vertical, what maximum height can now be reached by the projectile?
h/2
The area under the curve on a Force versus time (F vs. t) graph represents
impulse
Two massive objects are fixed in position. A third object is placed directly between the first two at the position at which the total gravitational force on the third object due to the two massive objects is zero. The object is displaced slightly toward one of the two massive objects, the total gravitational force on the third object is now
in the same direction the object is displaced
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
it would have skidded 4 times farther
Describe the type of spring "constant" need to produced a constant restoring force like curve (a) in Fig. 7-1
k must vary inversely with stretch
A horizontal force F pushes a block of mass m against a vertical wall. The coefficient of friction between the block and the wall is u. What value of F is necessary to keep the block from slipping down the wall?
mg/u
A weight lifter lifts a mass m at constant speed to a height h in time t. How much work is done by the weight lifter?
mgh
A plane, flying horizontally, releases a bomb, which explodes before hitting the ground. Neglecting air resistance, the center of mass of the bomb fragments, just after the explosion
moves along a parabolic path
A constant force is applied to an object that causes a certain displacement. If the angle between the force and the displacement is 135 degrees, the work done by this force is
negative
Two men, Joel and Jerry, push against a wall. Jerry stops after 10 min, while Joel is able to push for 5.0 min longer. Compare the work they do.
neither of them do any work
In the absence of air friction, an object dropped near the surface of the Earth experiences a constant acceleration of about 9.8 m/s^2. This means that the
speed of the object increases 9.8 meters per seconds during each second
A planet of mass M has a moon of mass m in a circular orbit of radius R. AN object is placed between the planet and the moon on the line joining the center of the planet to the center of the moon so that the net gravitational force on the object is zero. How far is the object placed from the center of the planet?
square root of M - square root of m divided by M-m multiplied by the square root of M
A figure of a dancer on a music box moves counterclockwise at constant speed around the path shown above. The path is such that the lengths of its segments, PQ, QR, RS, and SP, are equal. Arcs QR and SP are semicircles. Which of the following best represents the magnitude of the dancer's acceleration as a function of time t during one trip around the path, beginning at point P
starts off zero then goes straight up, then straight across, then straight down, then straight across at zero, then straight up, then straight across
A mass of 2 kg traveling at 3 m/s undergoes a one-dimensional elastic collision with a group of four 1-kg masses that are at rest in contact with each other and lined up in the same direction as the velocity of the 2-kg mass. As a result of the collision
the 2-kg mass comes to a stop and two of the 1-kg masses take off at 3 m/s
A students is testing the kinematic equations for uniformly accelerated motion by measuring the time it take for light-weight plastic balls to fall to the floor form a height of 3 meters in the lab. The student predicts the time to fall using g as 9.80 meters/seconds^2 but finds the measured time to be 35% greater. Which of the followings is the most likely cause of the large percent error
the acceleration of the plastic balls is not uniform
The graph above shows the velocity v as a function of time t for an object moving in a straight line. Which of the following graphs shows the corresponding displacement x as a function of time t for the same time interval
the curve slowly starts to increase
How do the escape velocities for two rockets, the first weighing 20 N and the second weighing 20,000 N compare
the escape velocity for the lighter rocket is the same as that for the heavier rocket
Jacques and George meet in the middle of a lake while paddling in their canoes. they come to a complete stop and talk for a while. When they are ready to leave, Jacques pushes George's canoe with a force F to separate the two canoes. What is correct to say about the final momentum and kinetic energy of the system?
the final momentum is zero kgm/s but the final kinetic energy is positive
A potential energy function for a certain system is given by U1(x)=Cx2+Bx3. the potential energy function for a second system is given by U2(x)=A+Cx2+Bx3, where A is a positive quantity. How does the force on system 1 relate to the force in system 2 at a given position
the force is identical in the two systems
A potential energy function for a certain system is given by U1(x)=Cx2+Bx3. The potential energy function for a second system is given by U2(x)=A+Cx2+Bx3, where A is a positive quantity. If an object begins at the same initial position with the same initial velocity in both systems, how is the motion in the two systems related
the motion in the two systems is identical
Two people are in a boat that is capable of a maximum speed of 5 kilometers per hour in still water, and wish to cross a river 1 kilometer wide to a point directly across from their starting point. If the speed of the water in the river is 5 kilometers per hour, how much time is required for the crossing
the point directly across from the starting point cannot be reached under these conditions
Consider a plot of the displacement (x) as a function of the applied force (F) for an ideal elastic spring. The slope of the curve would be
the reciprocal of the spring constant
An object slides off a roof 10 meters above the ground with an initial horizontal speed of 5 meters per second as shown above. The time between the object's leaving the roof and hitting the ground is most nearly
the square root of 2 seconds
At a particular instant, a stationary observer on the ground sees a package falling with speed v1 at an angle to the vertical. To a pilot flying horizontally at constant speed relative to the ground, the package appears to be falling vertically with a speed v2 at that instant. What is the speed of the pilot relative to the ground
the square root of v1^2-v2^2
In a collision between two unequal masses, how does the impulse imparted to the smaller mass by the larger mass compare with the impulse imparted to the larger mass by the smaller one?
they are equal
An elastic collision of two objects is characterized by the following
total momentum of the system is conserved and the total kinetic energy of the system remains constant
An object is released from rest at time t=0 and falls through the air, which exerts a resistive force such that the acceleration a of the the object is given be a=g-bv, where v is the object's speed and b is a constant. If limiting cases for large and small values of t are considered, which of the following is a possible expression for the speed of the object as an explicit function of time?
v=g(1-e^-bt)/b
An object is shot vertically upward into the air with a positive initial velocity. Which of the following correctly describes the velocity and acceleration of the object at its maximum elevation
velocity is zero and acceleration is negative
The velocity of a projectile at launch has a horizontal component vh and a vertical component vv. Air resistance is negligible. When the projectile is at the highest point of its trajectory, which of the following show the vertical and horizontal components of its velocity and the vertical component of its acceleration
vertical velocity is zero, horizontal velocity is vh, and vertical acceleration is g
A car travels forward with constant velocity. It goes over a small stone, which gets stuck in the groove of a tire. The initial acceleration of the stone, as it leaves the surface of the road, is
vertically upward
On a force vs. position graph, the area under curve is a representation of
work
A particle moves along the x-axis with a non-constant acceleration described by a=12t, where a is in meters per second squared and t is in seconds. If the particle starts from rest so that its speed v and position x are zero when t=0, where is it located when t=2 seconds
x=16 meters