Questions and Answers of Physics Everyday Phenomena

A net force of 20 N acting on a wooden block produces an acceleration of 4.0 m/s2 for the block. What is the mass of the block?
A ball with a mass of 2.5 kg is observed to accelerate at a rate of 6.0 m/s2. What is the size of the net force acting on this ball?
A single force of 40 N acts upon a 5-kg block. What is the magnitude of the acceleration of the block?
If the elevator cable breaks and you find yourself in a condition of apparent weightlessness as the elevator falls, is the gravitational force acting upon you equal to zero? Explain.
If you get into an elevator on the top floor of a large building and the elevator begins to accelerate downward, will the normal force pushing up on your feet be greater than, equal to, or less than
Suppose that a sky diver wears a specially lubricated suit that reduces air resistance to a small constant force that does not increase as the diver’s velocity increases. Will the sky diver ever
Two blocks with the same mass are connected by a string and are pulled across a frictionless surface by a constant force, F, exerted by a string (see diagram).a. Will the two blocks move with
Two masses, m1 and m2, connected by a string, are placed upon fixed friction less pulley as shown in the diagram. If m2 is larger than m1, will the two masses accelerate? Explain. m2 m1 Q29 Diagram
A toy battery-powered tractor pushes a book across a table. Draw separate diagrams of the book and the tractor identifying all of the forces that act upon each object. What is the reaction force
The upward normal force exerted by the floor on a chair is equal in size but opposite in direction to the weight of the chair. Is this equality an illustration of Newton’s third law of motion?
A mule is attempting to move a cart loaded with rock. Since the cart pulls back on the mule with a force equal in size to the force that the mule exerts on the cart (according to Newton’s third
A sprinter accelerates at the beginning of a 100-meter race and then tries to maintain maximum speed throughout the rest of the race.a. What external force is responsible for accelerating the runner
When a magician performs the tablecloth trick, the objects on the table do not move very far. Is there a horizontal force acting on these objects while the tablecloth is being pulled off the table?
A ball hangs from a string attached to the ceiling, as shown in the diagram.a. What forces act on the ball? How many are there?b. What is the net force acting on the ball? Explain.c. For each force
It is difficult to stop a car on an icy road surface. Is it also difficult to accelerate a car on this same icy road? Explain
The engine of a car is part of the car and cannot push directly on the car in order to accelerate it. What external force acting on the car is responsible for the acceleration of the car on a level
A boy sits at rest on the floor. What two vertical forces act upon the boy? Do these two forces constitute an action/ reaction pair as defined by Newton’s third law of motion? Explain.
Two identical cans, one filled with lead shot and the other with feathers, are dropped from the same height by a student standing on a chair.a. Which can, if either, experiences the greater force due
Is mass a force? Explain
The acceleration due to gravity on the moon is approximately one-sixth the gravitational acceleration near the Earth’s surface. If a rock is transported from Earth to the moon, will either its mass
The gravitational force acting on a lead ball is much larger than that acting on a wooden ball of the same size. When both are dropped, does the lead ball accelerate at the same rate as the wooden
Is the mass of an object the same thing as its weight? Explain.
Is Newton’s first law of motion explained by the second law? Explain. Why did Newton state the first law as a separate law of motion?
A car goes around a curve traveling at constant speed.a. Is the acceleration of the car zero in this process? Explain.b. Is there a non-zero net force acting on the car? Explain
An object moving horizontally across a table is observed to slow down. Is there a non-zero net force acting on the object? Explain.
Two equal forces act on an object in the directions pictured in the diagram below. If these are the only forces involved, will the object be accelerated? Explain, using a diagram. F2 F1 Q11
Suppose that a bullet is fired from a rifle in outer space where there are no appreciable forces due to gravity or air resistance acting on the bullet. Will the bullet slow down as it travels away
Is it possible that the object pictured in question 8 is moving, given the fact that the two forces acting on it are equal in size but opposite in direction? Explain.Picture From Question 8 10 N ,5 N
Two equal-magnitude horizontal forces act on a box as shown in the diagram. Is the object accelerated horizontally? Explain. -F Q8 Diagram
A 3-kg block is observed to accelerate at a rate twice that of a 6-kg block. Is the net force acting on the 3-kg block therefore twice as large as that acting on the 6-kg block? Explain.
Two equal forces act on two different objects, one of which has a mass ten times as large as the other. Will the more massive object have a larger acceleration, an equal acceleration, or a smaller
Did Galileo develop a more complete theory of motion than that of Newton? Explain.
How did Aristotle explain the continued motion of a thrown object. Does this explanation seem reasonable to you? Explain.
Aristotle believed that a force was necessary to keep an object moving. Where, in his view, did this force come from in the case of a ball moving through the air? Explain
Why did Aristotle believe that heavier objects fall faster than lighter objects? Explain.
Did Galileo’s work on motion precede in time that of Aristotle or Newton? Explain
An archeologist is running at 7 m/s with her hands outstretched above her head (1.95 m from feet to fingertips) while being chased by a tiger. She runs exactly horizontally off of a chasm and
A good pitcher can throw a baseball at a speed of 90 MPH. The pitcher’s mound is approximately 60 ft from home plate.a. What is the speed in m/s?b. What is the distance to home plate in meters?c.
A cannon is fired over level ground at an angle of 30° to the horizontal. The initial velocity of the cannonball is 400 m/s, but because the cannon is fired at an angle, the vertical component of
Two balls are released simultaneously from the top of a tall building. Ball A is simply dropped with no initial velocity, and ball B is thrown downward with an initial velocity of 12 m/s.a. What are
A ball is thrown straight upward with an initial velocity of 16 m/s. Use g = 10 m/s2 for computations listed here.a. What is its velocity at the high point in its motion?b. How much time is required
A projectile is fired at an angle such that the vertical component of its velocity and the horizontal component of its velocity are both equal to 30 m/s. a. Using the approximate value of g = 10
A ball rolls off a platform that is 5 meters above the ground. The ball’s horizontal velocity as it leaves the platform is 6 m/s.a. How much time does it take for the ball to hit the ground? (See
A ball rolls off a table with a horizontal velocity of 5 m/s. If it takes 0.6 seconds for it to reach the floor:a. What is the vertical component of the ball’s velocity just before it hits the
A ball rolls off a table with a horizontal velocity of 4 m/s. If it takes 0.5 seconds for the ball to reach the floor, how high above the floor is the tabletop? (Use g = 10 m/s2.)
A ball rolls off a shelf with a horizontal velocity of 6 m/s. At what horizontal distance from the shelf does the ball land if it takes 0.4 s to reach the floor?
A bullet is fired horizontally with an initial velocity of 900 m/s at a target located 150 m from the rifle.a. How much time is required for the bullet to reach the target?b. Using the approximate
Suppose that the gravitational acceleration on a certain planet is only 3.0 m/s2. A space explorer standing on this planet throws a ball straight upward with an initial velocity of 18 m/s.a. What is
At what time does the ball in exercise 7 reach the high point in its flight? (Use the approximate value of g = 10 m/s2, and remember that the velocity is equal to zero at the high point.)
How high above the ground is the ball in exercise 7:a. 1 second after it is thrown?b. 2 seconds after it is thrown?Exercise 7A ball is thrown upward with an initial velocity of 15 m/s, use the
A ball is thrown upward with an initial velocity of 15 m/s. Using the approximate value of g = 10 m/s2, what are the magnitude and direction of the ball’s velocity:a. 1 second after it is thrown?b.
A ball is dropped from a high building. Using the approximate value of g = 10 m/s2 find the change in velocity between the first and fourth second of its flight.
A ball is thrown downward with an initial velocity of 12 m/s. Using the approximate value of g = 10 m/s2, what is the velocity of the ball 1.0 seconds after it is released?
Suppose Galileo’s pulse rate was 80 beats per minute.a. What is the time in seconds between consecutive pulse beats?b. How far does an object fall in this time when dropped from rest?
A large rock is dropped from the top of a high cliff. Assuming that air resistance can be ignored and that the acceleration has the constant value of 10 m/s2 , how fast would the rock be traveling 5
A steel ball is dropped from a diving platform (with an initial velocity of zero). Using the approximate value of g = 10 m/s2,a. What is the velocity of the ball 0.8 seconds after its release?b. What
A football quarterback must hit a moving target while eluding onrushing linemen. Discuss the advantages and disadvantages of a hard low-trajectory throw to a higher lofted throw.
In shooting a basketball from greater than the free-throw range, what is the primary disadvantage of a high, arching shot? Explain.
In shooting a free throw in basketball, what is the primary advantage that a high, arching shot has over one with a flatter trajectory? Explain.
In the situation pictured in question 28, is the magnitude of the velocity important to the success of the shot? Explain.Data from problem 28 A Q28 Diagram
The diagram shows a wastebasket placed behind a chair. Three different directions are indicated for the velocity of a ball thrown by the kneeling woman. Which of the three directions A, B, or C is
Will a shot fired from a cannon at a 20° launch angle travel a longer horizontal distance than a 45° shot? Explain.
A cannonball fired at an angle of 70° to the horizontal stays in the air longer than one fired at 45° from the same cannon. Will the 70° shot travel a greater horizontal distance than the 45°
Assuming that the two trajectories in the diagram for question 23 represent throws by two different center fielders, which of the two is likely to have been thrown by the player with the stronger
For either of the trajectories shown in the diagram for question 23, is the velocity of the ball equal to zero at the high point in the trajectory? Explain. Data From Question 23In the diagram,
In the diagram, two different trajectories are shown for a ball thrown by a center fielder to home plate in a baseball game. Which of the two trajectories (if either), the higher one or the lower
An expert marksman aims a high-speed rifle directly at the center of a nearby target. Assuming that the rifle sight has been accurately adjusted for more distant targets, will the bullet hit the near
A ball rolls off a table with a horizontal velocity of 5 m/s. Is this velocity an important factor in determining the time that it takes for the ball to hit the floor? Explain.
A ball rolls off a table with a large horizontal velocity. Does the direction of the velocity vector change as the ball moves through the air? Explain.
Is it possible for an object to have a horizontal component of velocity that is constant at the same time that the object is accelerating in the vertical direction? Explain by giving an example, if
For the two balls in question 17, which, if either, has the larger total velocity when it hits the floor? Explain.
A ball rolling rapidly along a tabletop rolls off the edge and falls to the floor. At the exact instant that the first ball rolls off the edge, a second ball is dropped from the same height. Which
A ball rolls up an inclined plane, slows to a stop, and then rolls back down. Do you expect the acceleration to be constant during this process? Is the velocity constant? Is the acceleration equal to
A ball is thrown straight upward and then returns to the Earth. Does the acceleration change direction during this motion? Explain.
A ball is thrown straight upward. At the very top of its flight, the velocity of the ball is zero. Is its acceleration at this point also zero? Explain.
A rock is thrown straight upward reaching a height of 20 meters. On its way up, does the rock spend more time in the top 5 meters of its flight than in its first 5 meters of its flight? Explain
A ball thrown straight upward moves initially with decreasing upward velocity. What are the directions of the velocity and acceleration vectors during this part of the motion? Does the acceleration
A ball is thrown downward with a large starting velocity.a. Will this ball reach the ground sooner than one that is just dropped at the same time from the same height? Explain.b. Will this ball
The graph shows the velocity plotted against time for a certain falling object. Is the acceleration of this object constant? Explain. time velocity
A rock is dropped from the top of a diving platform into the swimming pool below. Will the distance traveled by the rock in a 0.1-second interval near the top of its flight be the same as the
Aristotle stated that heavier objects fall faster than lighter objects. Was Aristotle wrong? In what sense could Aristotle’s view be considered correct?
Two identical pieces of paper, one crumpled into a ball and the other left uncrumpled, are released simultaneously from inside the top of a large evacuated tube. Which one, if either, do you expect
Two identical pieces of paper, one crumpled into a ball and the other left uncrumpled, are released simultaneously from the same height above the floor. Which one, if either, do you expect to reach
A lead ball and an aluminum ball, each 1 in. in diameter, are released simultaneously and allowed to fall to the ground. Due to its greater density, the lead ball has a substantially larger mass than
The diagram shows the positions at intervals of 0.05 seconds of two balls moving from left to right. Are either or both of these balls accelerated? Explain. D-O-0-0- -O-00 в Q3 Diagram
The diagram shows the positions at intervals of 0.10 seconds of a ball moving from left to right (as in a photograph taken with a stroboscope that flashes every tenth of a second). Is the ball
A small piece of paper is dropped and flutters to the floor. Is the piece of paper accelerating at any time during this motion? Explain.
Just as car A is starting up, it is passed by car B. Car B travels with a constant velocity of 10 m/s, while car A accelerates with a constant acceleration of 4.5 m/s2, starting from rest.a. Compute
A car traveling in a straight line with an initial velocity of 14 m/s accelerates at a rate of 2.0 m/s2 to a velocity of 24 m/s.a. How much time does it take for the car to reach the velocity of 24
A car traveling due west on a straight road accelerates at a constant rate for 10 seconds increasing its velocity from 0 to 24 m/s. It then travels at a constant speed for 10 seconds and then
The velocity of a car increases with time as shown in the graph.a. What is the average acceleration between 0 seconds and 4 seconds?b. What is the average acceleration between 0 seconds and 8
A railroad engine moves forward along a straight section of track for a distance of 80 m due west at a constant speed of 5 m/s. It then reverses its direction and travels 20 m due east at a constant
Starting from rest, a car accelerates at a constant rate of 3.0 m/s2 for a time of 5 seconds.a. Compute the velocity of the car at 1 s, 2 s, 3 s, 4 s, and 5 s and plot these velocity values against
If a world-class sprinter ran a distance of 100 meters starting at his top speed of 11 m/s and running with a constant speed throughout, how long would it take him to cover the distance?
A runner moving with an initial velocity of 4.0 m/s slows down at a constant rate of -1.5 m/s2 over a period of 2 seconds.a. What is her velocity at the end of this time?b. What distance does she
A car moving with an initial velocity of 30 m/s slows down at a constant rate of -3 m/s2.a. What is its velocity after 3 seconds of deceleration?b. What distance does the car cover in this time?
A runner traveling with an initial velocity of 2.0 m/s accelerates at a constant rate of 1.2 m/s2 for a time of 2 seconds.a. What is his velocity at the end of this time?b. What distance does the
The velocity of a car decreases from 30 m/s to 18 m/s in a time of 4 seconds. What is the average acceleration of the car in this process?
Starting from rest, a car accelerates at a rate of 4.2 m/s2 for a time of 5 seconds. What is its velocity at the end of this time?
Starting from rest and moving in a straight line, a runner achieves a velocity of 7 m/s in a time of 2 s. What is the average acceleration of the runner?

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