PHYS 105 Exam 1 Assessment Questions And Correct Detailed Answers.

Choose the unit of speed below that is the basic SI unit of speed. a. Kilometers per hour b. leagues per day c. miles per hour d. meters per second - correct answer d. meters per second Suppose you are holding a meter stick, a ruler that is one meter long, which is marked on one side in cm and on the other side in inches. As you look at the cm side, approximately how many marks do you see? Assume no marks smaller than a cm. a. 30 marks b. 1 mark c. 1000 marks d. 100 marks e. 300 marks - correct answer d. 100 marks Physics has many applications in the biological sciences. Choose the INCORRECT description of application of physics in the biological sciences. a. explains sensory phenomena involving sound waves and visible light b. explains the dynamics of the human body c. explains the processes that occur in our brain to form memories and feel emotions d. medical diagnostic tools (X-ray, MRI, etc.) and treatments (radiotherapy) are based on phsyics. e. helps describe the properties of cell walls and membranes - correct answer c. explains the processes that occur in our brain to form memories and feel emotions Consider a cannon that can fire a cannonball at a certain speed at angles ranging from 0-90 degrees above the horizontal. If the initial speed of the cannonball remains the same as you vary the angle of the cannon, at what angle do you need to fire the cannonball so that it will reach the maximum range possible? a. 45 degrees b. 90 degrees c. 15 degrees d. 75 degrees - correct answer a. 45 degrees Consider physical scenarios given below and choose the situation in which the velocity is zero, but the acceleration is not zero. a. a ball that is thrown directly upward at the top of its trajectory b. a car moving down a straight section of freeway at a constant speed of 60 mph c. a car as it slows down to a stop, but before it has come to a complete stop d. a ball that is thrown across the field at the top of its trajectory - correct answer a. a ball that is thrown directly upward at the top of its trajectory Which of the following situations describes where acceleration is zero? a. speeding up or slowing down while moving b. starting to move from rest c. moving at a constant speed in a straight line d. moving in a constant speed along a circle - correct answer c. moving at a constant speed in a straight line Your friend Sue claims that a car making a turn at a constant speed (of 40 mph, for example) is in fact "accelerating," in the sense used in physics classes (like this one). Which explanation below mostly correctly describes why your friend Sue is correct? a. Sue is correct bc when a car makes a turn moving at a constant speed (of 40 mph), its velocity is changing. An object is said to accelerate when its velocity changes b. Sue is correct bc you have insufficient evidence to disprove her claim. In science, all claims are presumed correct until proven incorrect and must be given a serious consideration c. Sue is correct because when the car makes a turn, you feel the centrifugal force pushing you to the outer edge of the turn. According to Newton's Second Law, F = ma, so you are accelerating due to the centrifugal force d. Sue is not correct. If a car moves at a constant speed (of 40 mph), then it is not speeding up - correct answer a. Sue is correct bc when a car makes a turn moving at constant speed (of 40 mph), its velocity is changing. An object is said to accelerate when its velocity changes Which of the following is a valid unit for acceleration? a. m/s b. horsepower c. m/s^2 d. m^2/s^2 - correct answer c. m/s^2 During a lecture demonstration, a professor places two coins on the edge of a table. She then flicks one of the coins horizontally launching it off the table, simultaneously nudging the other just over the edge. Which of these two coins hit the floor first? a. the coin that is nudges just over the edge hits the floor first b. the coin that is launched horizontally off the table hits the floor first c. both coins hit the floor at the same time - correct answer c. both coins hit the floor at the same time Which of the following INCORRECTLY defines or describes "free-fall"? a. if an object is moving upward, it cannot be considered to be in a free-fall b. in free-fall motion, air and wind resistance are ignored. c. objects in free-fall are being affected only by gravity d. an object in free-fall is accelerating at gravitational acceleration - correct answer a. if an object is moving upward, it cannot be considered to be in a free-fall As two boys are playing in the outdoors, one boy hangs from a tree while the other boy aims a water balloon cannon directly at him. Choose the statement below which most correctly predicts what will happen in the next moment, depending on what the boy who hangs from the tree decides to do. a. if the boy lets go off the tree the moment the water balloon is fired, the boy will avoid getting hit by the water balloon, as the cannon was aimed directly where he was b. if the boy continues to hold onto the tree, he will get hit by the water balloon, as the cannon is aimed directly at him c. if the boy lets go of the tree the moment the water balloon is fired, the boy will definitely get hit by the water balloon, as the water balloon's trajectory curves downward along w/ the falling boy d. if the boy continues to hold onto the tree, he will definitely avoid getting hit by the water balloon, as the water balloon will curve do - correct answer c. if the boy lets go of the tree the moment the water balloon is fired, the boy will definitely get hit by the water balloon, as the water balloon's trajectory curves downward along w/ the falling boy For this question, let the right direction be positive (+) and the left direction be negative (-). If a bird flies to the right while speeding up, which of the statements below correctly describes the signs of velocity and acceleration? a. velocity is + and acceleration is - b. velocity is - and acceleration is + c. velocity and acceleration are both + d. velocity and acceleration are both - - correct answer c. velocity and acceleration are both + Which of the following statements correctly describes or defines "velocity"? a. velocity is given by acceleration b. velocity is the speed of motion c. velocity is the rate of change of position d. velocity is how fast something is moving - correct answer c. velocity is the rate of change of position Timmy has fallen in a well! Firefighters are rescuing Timmy by securing him to a harness and pulling him upward. Timmy considers his situation as he is being pulled upward at a steady speed. Which statement below most correctly compares the tension force pulling him up with Timmy's weight pulling him downward? a. additional info is needed to compare tension force to Timmy's weight b. tension force is less than Timmy's weight c. tension force is greater than Timmy's weight d. tension force is equal to Timmy's weight - correct answer d. tension force is equal to Timmy's weight Consider the gravitational force between Earth and an apple that falls from a tree. Evaluate the following statements and choose the INCORRECT statement a. the gravitational acceleration of the apple is equal in magnitude to the gravitational acceleration of the Earth b. the magnitude of gravitational force on the apple by the Earth is equal to the magnitude of gravitational force on the Earth by the apple c. the acceleration of the apple due to gravitational force on the apple is greater than the acceleration of the Earth due to gravitational force on the Earth d. the gravitational force on the apple by the Earth is in opposite direction from the gravitational force on the Earth by the apple - correct answer a. the gravitational acceleration of the apple is equal in magnitude to the gravitational acceleration of the Earth Consider the following scenario in application of Newton's Laws. A box of mass 55 kg sits on a wooden floor. Tommy comes along and tries to push the box horizontally. As Tommy tries to push the box with a force of 21 N, the