Section 1
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A block of weight W is pulled along a horizontal surface at constant speed v by a force F, which acts at an angle of q with the horizontal, as shown above. The normal force exerted on the block by the surface has magnitude
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Cards (58)
Section 1
(50 cards)
A block of weight W is pulled along a horizontal surface at constant speed v by a force F, which acts at an angle of q with the horizontal, as shown above. The normal force exerted on the block by the surface has magnitude
W-Fsinq
Two bodies of masses 5 and 7 kilograms are initially at rest on a horizontal frictionless surface. A light spring is compressed between the bodies, which are held together by a thin thread. After the spring is released by burning through the thread, the 5 kilogram body has a speed of 0.2 m/s. The speed of the 7 kilogram body is
1/7 m/s
A rod on a horizontal tabletop is pivoted at one end and is free to rotate without friction about a vertical axis, as shown above. A force F is applied at the other end, at an angle q to the rod. If F were to be applied perpendicular to the rod, at what distance from the axis should it be applied in order to produce the same torque?
L sin q
The displacement x of an object moving along the x-axis is shown above as a function of time t. The acceleration of this object must be
Zero
A horizontal, uniform board of weight 125 N and length 4 m is supported by vertical chains at each end. A person weighing 500 N is sitting on the board. The tension in the right chain is 250 N. What is the tension in the left chain?
375 N
A uniform rope of weight 50 newtons hangs from a hook as shown above. A box of weight 100 newtons hangs from the rope. What is the tension in the rope?
varies throughout the rope
What is the speed of the gas in the left end of the pipe?
20/p m/s
An open cart on a level surface is rolling without frictional loss through a vertical downpour of rain, as shown above. As the cart rolls, an appreciable amount of rainwater accumulates in the cart. The speed of the cart will
decrease because of conservation of momentum
Each of the beakers shown above is filled to the same depth h with liquid of density p. The area A of the flat bottom is the same for each beaker. Which of the following ranks the beakers according to the net downward force exerted by the liquid on the flat bottom, from greatest to least force
None of the above
A plastic ball with a volume of 100 cm3 floats in water with half its volume submerged. What is the mass of the ball?
50 g
A large open tank with diameter 10 meters is filled with water to a depth of 20 meters. Which is the best estimate of the total fluid pressure at the bottom of the tank?
300 kPa
The figure above shows an object of mass 0.4 kg that is suspended from a scale and submerged in a liquid. If the reading on the scale is 3 N, then the buoyant force that the fluid exerts on the object is most nearly
1.0 N
A spring scale calibrated in kilograms is used to determine the density of a rock specimen. The reading on the spring scale is 0.45 kg when the specimen is suspended in air and 0.36 kg when the specimen is fully submerged in water. If the density of water is 1000 kg/m3, the density of the rock specimen is
5.0 x 10^3 kg/m3
When an object of weight W is suspended from the center of a massless string as shown above. the tension at any point in the string is
W/(2cosq)
Two objects, X and Y, accelerate from rest with the same constant acceleration. Object X accelerates for twice the time as object Y. Which of the following is true of these objects at the end of their respective periods of acceleration?
Object X has traveled four times as far as object Y.
What water pressure is required at a faucet to be able to spray water to a height of 10 meters?
1 *10^5 Pa
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
-36m
A T-shaped tube with a constriction is inserted in a vessel containing a liquid, as shown above. What happens if air is blown through the tube from the left, as shown by the arrow in the diagram?
The liquid level in the tube rises to a level above the surface of the liquid surrounding the tube.
A 3.0 kg block hanging from a spring scale is submerged in a beaker of water until the spring scale reads 20 N. What is the buoyant force on the block?
10 N
Balsa wood with an average density of 130 kg/m3 is floating in pure water. What percentage of the wood is submerged?
13%
The graph above represents position x versus time t for an object being acted on by a constant force. The average speed during the interval between 1 s and 2 s is most nearly
6 m/s
An object weighing 120 N is set on a rigid beam of negligible mass at a distance of 3 m from a pivot, as shown above. A vertical force is to be applied to the other end of the beam a distance of 4 m from the pivot to keep the beam at rest and horizontal. What is the magnitude F of the force required?
90N
A push broom of mass m is pushed across a rough horizontal floor by a force of magnitude T directed at angle q as shown above. The coefficient of friction between the broom and the floor is m. The frictional force on the broom has magnitude
m(mg+Tsinq)
A ball of mass 0.4 kg is initially at rest on the ground. It is kicked and leaves the kicker's foot with a speed of 5.0 m/s in a direction 60° above the horizontal. The magnitude of the impulse imparted by the ball to the foot is most nearly
2 N·s
A ball attached to a string is whirled around in a horizontal circle having a radius r. If the radius of the circle is changed to 4r and the same centripetal force is applied by the string, the new speed of the ball is which of the following?
Twice the original speed
What is the magnitude of the work done by the frictional force exerted on the block by the rough section of the surface?
24J
An ideal fluid flows through a pipe made of two sections with diameters of 1 cm and 3 cm, respectively. By what factor would you have to multiply the velocity of the liquid flowing through the 1 cm section to obtain the velocity of liquid flowing through the 3 cm section?
1/9
constant force of 900 N pushes a 100 kg mass up the inclined plane shown above at a uniform speed of 4 m/s. The power developed by the 900 N force is most nearly
3600 W
A truck traveled 400 meters north in 80 seconds, and then it traveled 300 meters east in 70 seconds. The magnitude of the average velocity of the truck was most nearly
3.3 m/s
The magnitude of the frictional force along the plane is most nearly
6 N
A ball is thrown with an initial speed of 20 m/s at an angle of 60° to the ground. If air resistance is negligible, what is the ball's speed at the instant it reaches its maximum height from the ground?
10 m/s
An object is released from rest on a planet that has no atmosphere. The object falls freely for 3.0 meters in the first second. What is the magnitude of the acceleration due to gravity on the planet?
6 m/s
For an ideal fluid flowing through a horizontal pipe, Bernoulli's equation states that the sum of the pressure and energy per unit volume along the pipe does which of the following? (Assume measurements are taken along the pipe in the direction of fluid flow.)
remains constant as the pipe diameter increases
The speed of the gas in the right end of the pipe is how many times the speed in the left end?
4
A ball of mass m is suspended from two strings of unequal length as shown above. The tensions T1 and T2 in the strings must satisfy which of the following relations?
T1 < T2
How does an air mattress protect a stunt person landing on the ground after a stunt?
lengthens time reduces force
The pressure exerted on the bottom of a dam by the water in the reservoir created by the dam depends on the
Depth of the water at the dam
A railroad flatcar of mass 2,000 kilograms rolls to the right at 5 meters per second and collides with a flatcar of mass 3,000 kilograms that is rolling to the left at 10 meters per second. The flatcars couple together. Their speed after the collision is
4 m/s
The speed of the ball at point II is most nearly
4.5 m/s
Which of the following statements is an expression of the equation of continuity?
Fluid flows faster through a narrower pipe
A car initially travels north and then turns to the left along a circular curve. This causes a package on the seat of the car to slide toward the right side of the car. Which of the following is true of the net force on the package while it is sliding?
There is not enough force directed toward the center of the circle to keep the package from sliding
Two people of unequal mass are initially standing still on ice with negligible friction. They then simultaneously push each other horizontally. Afterward, which of the following is true?
The momenta of the two people are of equal magnitude
To weigh a fish a person hangs a tackle box of mass 3.5 kilograms and a cooler of mass 5 kilograms from the ends of a uniform rigid pole that is suspended by a rope attached to its center. The system balances when the fish hangs at a point 1/4 of the rod's length from the tackle box. What is the mass of the fish?
3 kg
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 m/s
An object has a weight W when it is on the surface of a planet of radius R. What will be the gravitational force on the object after it has been moved to a distance of 3R from the center of the planet?
1/9 W
A tennis ball of mass m rebounds from a racquet with the same speed v as it had initially. as shown above. The magnitude of the momentum change of the ball is
2mvcosq
A 2-kilogram block rests at the edge of a platform that is 10 meters above level ground. The block is launched horizontally from the edge of the platform with an initial speed of 3 meters per second. Air resistance is negligible. The time it will take for the block to reach the ground is most nearly
1.4s
A new planet is discovered that has twice the Earth's mass and twice the Earth's radius. On the surface of this new planet, a person who weighs 500 N on Earth would experience a gravitational force of
250N
What is the kinetic energy of the rock just before it hits the ground?
½ mv02+mgh
A block of mass 3m can move without friction on a horizontal table. This block is attached to another block of mass m by a cord that passes over a frictionless pulley, as shown above. If the masses of the cord and the pulley are negligible, what is the magnitude of the acceleration of the descending block?
g/4
Section 2
(8 cards)