Physics Sem 1 Review
An object is sliding to the right along a straight line on a horizontal surface. The graph shows the object's velocity as a function of time. What is the object's displacement during the time depicted in the graph?
0m
Two blocks of masses 1.0 kg and 2.0 kg, respectively, are pushed by a constant applied force F across a horizontal frictionless table with constant acceleration such that the blocks remain in contact with each other, as shown above. The 1.0 kg block pushes the 2.0 kg block with a force of 2.0 N. The acceleration of the two blocks is
1.0 m/s2
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 4R from the center of the planet?
1/16 W
A ball is attached to one end of a string such that the ball travels in a vertical circular path near Earth's surface. The force diagram of the ball at its lowest point in the circular path is shown above. What is the net centripetal force exerted on the ball?
15N
The figure above shows the forces exerted on a block that is sliding on a horizontal surface: the gravitational force of 40 N, the 40 N normal force exerted by the surface, and a frictional force exerted to the left. The coefficient of friction between the block and the surface is 0.20. The acceleration of the block is most nearly Responses
2.0 m/s2 to the left
A student performs an experiment in which the horizontal position of a toy car is recorded on ticker tape from a device that places dots on the tape in equal time intervals. The series of dots in the figure represents the motion of an object moving from the negative direction to the positive direction along the horizontal direction. The time interval between each recorded dot is 1s. Which of the following experiments could the student have conducted to create the data shown on the ticker tape? Responses
A toy car that initially increases its speed, travels at a constant speed, and then decreases its speed.
Balls 1 and 2 are each thrown horizontally from the same height above level ground, but ball 2 has a greater initial velocity after leaving the thrower's hand. If air resistance is negligible, how do the accelerations of the balls and the times it takes them to hit the ground compare?
Acceleration a Time to Hit Ground Equal Equal
A student wants to launch a toy dart toward a target that hangs from a light string. At time T=0, the dart is launched with an initial speed V0 at an angle O0 above the horizontal ground. At the instant the dart is launched, the string is cut such that the target begins to fall straight down. The positive horizontal direction is considered to be to the right, and the positive vertical direction is considered to be up. Which of the following graphs could represent the vertical component of the velocity as a function of time for the dart and the target immediately after the dart is launched and the target begins to fall?
Dart Target Positive but going downward At 0 but going downward
A student wants to launch a toy dart toward a target that hangs from a light string. At time T=0, the dart is launched with an initial speed V0 at an angle O0 above the horizontal ground. At the instant the dart is launched, the string is cut such that the target begins to fall straight down. The positive horizontal direction is considered to be to the right, and the positive vertical direction is considered to be up. Figure 1 shows a displacement-versus-time graph for the dart. Figure 2 shows a displacement-versus-time graph for the target. For both graphs, the component of the displacement is not indicated. Which displacement component, horizontal or vertical, is represented by the graph for each object?
Dart Target Vertical Vertical
A vertical spring launcher is attached to the top of a block and a ball is placed in the launcher, as shown in the figure. While the block slides at constant speed to the right across a horizontal surface with negligible friction between the block and the surface, the ball is launched upward. When the ball reaches its maximum height, what will be the position of the ball relative to the spring launcher?
Directly above the spring launcher
Blocks A and B, of masses M and 2M, respectively, are connected by a light string and pulled across a surface of negligible friction with a constant force F1, as shown above. The acceleration of the blocks is A. The force of the string pulling block B forward has magnitude F2. Which of the following claims correctly describes the relationship between the magnitude of the forces acting on the blocks?
F1 is greater than F2.
Object X and object Y are at rest on a horizontal surface. Object X is in contact with object Y. The force diagrams for both objects are shown above. Which two forces make up an action-reaction pair?
F3 and F6, because both forces are exerted on different objects, have the same magnitude, and are in opposite directions.
A student wants to launch a toy dart toward a target that hangs from a light string. At time T=0, the dart is launched with an initial speed V0 at an angle O0 above the horizontal ground. At the instant the dart is launched, the string is cut such that the target begins to fall straight down. The positive horizontal direction is considered to be to the right, and the positive vertical direction is considered to be up. A student makes the necessary measurements to create the graph shown, which represents the vertical component of the velocity as a function of time for the dart and for the target from T=0 until the instant the dart hits the target. At T=0, the target is a vertical distance ℎ above the dart. The curves for the dart and the target each have the same area between them and the horizontal axis. Both curves also have the same slope. Which of the following is the best method to determine the distance ℎ f
Find twice the area under the curve for the dart's data.
The figures show a cart moving over the top of a hill (Case 1), moving at the bottom of a dip (Case 2), and moving at the top of a vertical loop (Case 3). In each case, the normal force acting on the car is Fn and the weight of the car is Fg. In which case is it always true that Fn>Fg, and in which case is it always true that Fn<Fg?
Fn>Fg Fn<Fg Case 2 Case 1
The diagram above represents the forces exerted on a box that a child is holding. Fn represents the force applied by the child's hand, and Fg represents the weight of the box. The child begins to raise the box with increasing speed. Which of the following claims is correct about force Fℎ that is exerted by the box on the child's hand as the box is being raised?
Fℎ=Fn, where Fn is larger as the box is being raised than when it was being held.
A ball of mass M swings in a horizontal circle at the end of a string of radius R at a constant tangential speed V0. A student gradually pulls the string inward such that the radius of the circle decreases while keeping the tangential speed V0 of the ball constant, as shown above. Which of the following graphs best represents the acceleration A of the ball as a function of time T?
Graph: constant than Increasing up exponentially
At time T=0, a projectile is launched from the top of a cliff at an angle of 30 degrees below the horizontal. Which of the following pairs of graphs best represents the horizontal displacement Δx and the vertical velocity component Vvert of the projectile as a function of time T?
Horizontal Displacement Vertical Velocity Component Starting at 0, straight upward at -1 downward
The toy car shown in the figure above enters the vertical circular loop with an initial velocity and moves completely around the loop without friction. If the car has no means of self-propulsion, which of the following is true of the car's acceleration at the instant it is at point P ? Responses
It has components both downward and toward the center of the circle.
A lion is running at constant speed toward a gazelle that is standing still, as shown in the top figure above. After several seconds, the gazelle notices the lion and accelerates directly toward him, hoping to pass the lion and force him to reverse direction. As the gazelle accelerates toward and past the lion, the lion changes direction and accelerates in pursuit of the gazelle. The lion and the gazelle eventually each reach constant but different speeds. Which of the following sets of graphs shows a reasonable representation of the velocities of the lion and the gazelle as functions of time?
Lion starts constant below 0, Gazelle starts constant AT 0 then increases
Refer to the following material to answer the questions. The stacks of boxes shown in the figure above are inside an elevator that is moving upward. The masses of the boxes are given in terms of the mass M of the lightest box. Assume the elevator is moving at constant speed, and consider the bottom box in the stack that has two boxes of mass 2M. Let Ffloor be the force exerted by the floor on the box, Fg be the force exerted by gravity on the box, and Fbox be the force exerted by the top box on the bottom box. Which of the following best represents the forces exerted on the bottom box?
Pictures: 1 Ffloor going up Double Fg and Fbox down
A ball is thrown straight up in the air. When the ball reaches its highest point, which of the following is true?
None of the above
Object A is released from rest at height h. At the same instant, object B is thrown downward from the same location. Which of the following graphs of speed of v as a function of time t is correct for the two objects? Responses
Picture: B above A parallel to each other
One end of a string is attached to a vertical pole with the other end of the string attached to a ball that swings in a horizontal circular path, as shown. Which of the following free body diagrams represents the forces exerted on the ball?
Picture: Big arrow pointing left corner and arrow point straight down
A cart of mass M is moving with speed V on a smooth track when it encounters a vertical loop of radius R, as shown above. The cart moves along the inside of the entire loop without leaving the track. All frictional forces are negligible. Which of the following free-body diagrams shows the force or forces exerted on the cart at point Q ?
Picture: F normal Long arrow pointing right F gravity short arrow pointing down
Three blocks are pushed along a rough surface by a force with magnitude P, as shown above. Fc is the magnitude of the contact force between blocks 2 and 3, and Ff, Fn, and Fg are the magnitudes of the friction, normal, and gravitational forces on block 3, respectively. Which of the following is a correct free-body diagram for block 3?
Picture: Fn up, long Ff left, SHORT Fg down, long Fc right, long
An object slides across a horizontal surface such that it slows down due to the force of friction that is exerted on the object. The object and the direction of its displacement are shown in the figure. Which of the following free-body diagrams could represent the forces that are exerted on the object?
Picture: Fnormal going up short Ffriction going left very short Fgravity going down short
A block is pulled along a surface of negligible friction by a spring scale that exerts a force F on the block. The mass of the block is 4kg, and the spring scale reads 10N. Which of the following free-body diagrams can be used to show the magnitude and direction of all the forces exerted on the block as it is pulled along the surface?
Picture: Fnormal: long Fspring: very short Fgravity: long
Three identical blocks, X, Y, and Z, hang from identical strings, as shown in the figure. Which of the following free-body diagrams could represent the forces exerted on block Y?
Picture: Ftension: up Ftension down = to Fgravity
A projectile launched from a cliff at time T=0 follows the path indicated by the dashed line in the above figure. The axes indicate the positive horizontal and vertical directions. Which of the following graphs could represent the projectile's motion? Responses
Picture: Vertical Velocity- 0 in the middle and line going to the right downward
A box is given a sudden push up a ramp. Friction between the box and the ramp is not negligible. Which of the following diagrams best represents the directions of the actual forces acting on the box as it moves upward after the push?
Picture: arrow going up and down and left (downhill)
The figure above represents the orbits of two planets of equal mass that orbit their star in the counterclockwise direction as a double-planet system. From the point of view of an observer on either planet, the planets appear to orbit each other while also orbiting the star. The dots on the orbits represent the position of the planets at time t0, and X is the position of their center of mass at that time. Which of the following arrows best represents the acceleration of the center of mass of the double-planet system when it is at point X ? Responses
Picture: arrow points left downward
A steel ball supported by a stick rotates in a circle of radius r, as shown above. The direction of the net force acting on the ball when it is in the position shown is indicated by which of the following?
Picture: dotted circle with arrow pointing towards the center inner of circle
The position and velocity of a car moving along a straight road are recorded as functions of time, as shown in the graphs above. Which of the following correctly describes the car's speed and acceleration?
Speed Acceleration Decreasing Positive
Planet 1 orbits Star 1 and Planet 2 orbits Star 2 in circular orbits of the same radius. However, the orbital period of Planet 1 is longer than the orbital period of Planet 2. What could explain this?
Star 1 has less mass than Star 2
A kitten sits in a lightweight basket near the edge of a table. A person accidentally knocks the basket off the table. As the kitten and basket fall, the kitten rolls, turns, kicks, and catches the basket in its claws. The basket lands on the floor with the kitten safely inside. If air resistance is negligible, what is the acceleration of the kitten-basket system while the kitten and basket are in midair?
The acceleration is directed downward with magnitude equal to g because the system is a projectile.
Two blocks are connected by a rope, as shown above. The masses of the blocks are 5 kg for the upper block and 10 kg for the lower block. An upward applied force of magnitude F acts on the upper block. The system is moving and accelerating upward. A pair of scissors cuts the rope. Which of the following describes the motion of the 10 kg block immediately after the rope has been cut?
The block continues to move upward but begins to accelerate downward.
A space station has a mass M and orbits Earth in a circular orbit at a height above Earth's surface. An astronaut in the space station appears weightless because the astronaut seems to float. Which of the following claims is true about the force exerted on the astronaut by Earth?
The force exerted on the astronaut by Earth is equal to the force exerted on Earth by the astronaut.
A planet travels in an elliptical path around a star, as shown in the figure. As the planet gets closer to the star, the gravitational force that the star exerts on the planet increases. Which statement of reasoning best supports and correctly identifies what happens to the magnitude of the force that the planet exerts on the star as the planet gets closer to the star? Responses
The force increases because it is part of a Newton's third law pair of forces with the force that the star exerts on the planet.
A tennis ball is thrown against a vertical concrete wall that is fixed to the ground. The ball bounces off the wall. How does the force exerted by the ball on the wall compare with the force exerted by the wall on the ball? Responses
The forces exerted by the ball and the wall have the same magnitude.
An astronaut stands on the surface of an asteroid. The astronaut then jumps such that the astronaut is no longer in contact with the surface. The astronaut falls back down to the surface after a short time interval. Which of the following forces CANNOT be neglected when analyzing the motion of the astronaut? Responses
The gravitational force between the astronaut and the asteroid
A cart of mass M is moving with speed V on a smooth track when it encounters a vertical loop of radius R, as shown above. The cart moves along the inside of the entire loop without leaving the track. All frictional forces are negligible. Which of the following must be true for the cart to remain on the track when it is at point P ?
The net force exerted on the cart must be equal to or greater than the weight of the cart.
Refer to the following material for answering group of questions. A crate is on a horizontal frictionless surface. A force of magnitude F is exerted on the crate at an angle θ to the horizontal, as shown in the figure above, causing the crate to slide to the right. The surface exerts a normal force of magnitude FN on the crate. As the crate slides a distance d, it gains an amount of kinetic energy ∆K. While F is kept constant, the angle θ is now doubled but is still less than 90o. Assume the crate remains in contact with the surface. How does the new normal force exerted on the crate compare to FN ? Responses
The new normal force is less than FN.
An object attached to one end of a string moves in a circle at constant speed. Which of the following is correct? Responses
The object is accelerating as it moves.
The motion of an object is shown in the velocity-time graph. Which best describes the motion of the object? Responses
The object travels in the same direction for the entire time.
An object's velocity v as a function of time t is given in the graph above. Which of the following statements is true about the motion of the object?
The object's initial and final positions are the same.
Two identical books are stacked on a table. A third identical book is then placed on top of the first two, causing an increase in the normal force exerted by the bottom book on the middle book. Which of the following is a correct explanation for the increase in this normal force? Responses
The third book produces an additional downward force on the middle book, thus increasing the upward force exerted by the bottom book to maintain equilibrium.
A comet passes by a planet with a speed v0 such that the comet travels in a straight line at the instant shown in the figure. The comet's tangential acceleration, centripetal acceleration, and force due to gravity from the planet at this location are provided in the table. Astronomers observe that the comet continues to travel in a nearly straight line, even though calculations show that the gravitational force exerted by the planet should cause the comet to move in a circular orbit. Why does the comet not travel in a circular path around the planet after the instant shown in the figure? Responses
There must be another object such that the gravitational forces exerted on the comet are balanced at this location.
Two students want to determine the speed at which a ball is released when thrown vertically upward into the air. One student throws the ball into the air while the other student measures the total time that the ball is in the air. The students use a meterstick to measure the release height of the ball. Which of the following equations should the students use to determine the speed at which the ball was released?
Use Y=y0+Vy0T+1/2ayT2 from the moment in time in which the ball was released to the moment in time in which the ball hits the ground.
A cart is constrained to move along a straight line. A varying net force along the direction of motion is exerted on the cart. The cart's velocity v as a function of time t is shown in the graph above. The five labeled points divide the graph into four sections. Which of the following correctly ranks the magnitude of the average acceleration of the cart during the four sections of the graph?
aCD > aAB > aDE > aBC
An object is thrown with an initial speed v near the surface of Earth. Assume that air resistance is negligible and the gravitational field is constant.
downward and constant