Physics/PreAP Physics Midterm Review 2013/2014 The midterm exam includes 50 multiple-choice questions. You will have access to a standard formula chart (copies available in the classroom) as well as a calculator (graphing or scientific). Note that this document does not include sample questions for every target and should not be your sole source of review. Italicized targets are for PreAP Physics only. **In general, you should know how to recognize a scenario that fits each model as well as the definitions and units (where appropriate) for each of the following concepts: accuracy, precision, linear relationship between variables, quadratic relationship, inverse-square relationship, position, distance, displacement, speed, velocity, acceleration, force, net/unbalanced force, free-body diagram, mass, weight, Newton s 3 laws, torque, centripetal force, centripetal acceleration, tangential velocity, universal gravitation, scalar, vector, momentum, impulse, conservation of momentum 0) Scientific Methods 0.1 I can distinguish between accuracy and precision in data. 0.2 I can use significant figures to precisely report measurements. 0.3 I can apply significant figure rules for basic arithmetic. a) 1.12 + 2.8 =? b) 1.50 x 20 =? 0.4 I can describe the meaning of the slope for a linear relationship between variables. 1) Constant Velocity Particle Model (CVPM) 1.1 I can distinguish between and determine position, displacement, and distance. a) A toy car has position x = 0 m. It is driven +5 m, then -10 m, then -2 m. What is the car s final position, total distance traveled, and displacement? 1.2 I can draw and interpret (slope and area under graph) position-time and velocity-time graphs to represent the motion of an object moving with constant velocity. a) The position of a toy car is measured each second for 5 seconds. The data is as follows: 0 m, 2 m, 5 m, 7 m, 9 m. Sketch and label a position-time and velocity-time graph for the motion of the car and explain the meaning of the slope for each graph. (PreAP Only) Use your velocity-time graph to determine the displacement of the car at 3.5 seconds. b) A red toy car moves with constant velocity 4.5 m/s. Sketch and label the car s position-time and velocity-time graphs. c) On your graphs from part (b), add the position-time and velocity-time graphs for a blue toy car moving backwards whose velocity is less than the red car. d) For the toy car s position-time graph to the right, describe the motion of the car, then calculate the velocity of the car from t = 0 s to t = 40 s and from t = 0 s to t = 55 s. 1.3 I can solve problems using the CVPM. a) A toy car drives from one end of the room to the other, a distance of 13 m. The trip took 8 seconds. What is the average velocity of the car? b) Suppose that halfway through the journey in part (a), the car was stopped for 10 seconds to have the batteries replaced. What is the average velocity of the car including the stop? c) A racecar reaches a speed of 95 m/s after it is 450 meters past the starting line. If the car travels at a constant speed of 95 m/s for the next 12.5 s, how far will the car be from the starting line? 1
2) Constant Acceleration Particle Model (CAPM) 2.1 I can draw and interpret (slope and area under graph) position-time, velocity-time, and accelerationtime graphs to represent the motion of an object moving with constant acceleration. a) The position of a bowling ball as it falls, from rest, off a cliff is measured each second. Sketch and label a position-time and velocity-time graph for the motion of the bowling ball and explain the meaning of the slope for each graph. b) Use the position-time graph to the right to answer the following questions. i. Describe the motion shown. Be specific. ii. Calculate the object s instantaneous velocity at t = 5 s. iii. Assuming the object s initial velocity was 10 m/s and its final velocity is 0 m/s, determine its acceleration. iv. Sketch the corresponding velocity-time graph. 2.2 I can solve problems for objects in free-fall. a) All objects fall with the same acceleration regardless of mass. True or false? Explain. b) Bart Simpson falls from a treehouse and lands on the ground 1.5 s later. How tall is the treehouse? c) Miley Cyrus is dropped off the edge of a 225 m tall cliff. How much time will it take for her to reach the ground and how fast will she be traveling when she gets there? 2.3 I can solve problems using the CAPM. a) A bowling ball, initially at rest, accelerates at a constant rate of 4.0 m/s 2 for 6 s. How fast will the ball be traveling at t = 6 s? b) A tailback initially running at a velocity of 5.0 m/s becomes very tired and slows down at a uniform rate of 0.25 m/s 2. Sketch a graph of the athlete s position vs. time and his velocity vs. time, then determine how fast will he be running after going an additional 10 meters? c) A car traveling at 12.0 m/s accelerates for 4.0 s in order to pass another vehicle, traveling 150 m during that time. What was the car s speed at the end of the time period? 2.4 I can classify and solve problems using one-dimensional kinematics concepts. 3) Balanced Forces Particle Model (BFPM) 3.1 I can relate balanced forces to an object s constant velocity motion. a) For each of the following scenarios, state whether the forces are balanced (B) or unbalanced (U). i. A box resting on the ground ii. A box falling from the sky iii. A satellite orbiting the earth iv. A car rounding a curve v. A hovercraft moving along the floor with constant velocity 3.2 I can distinguish between and determine mass and weight of an object. a) The gravitational force on the surface of the moon is only about 1/6 as strong as the gravitational force on Earth. i. What is the weight of a 60 kg person on Earth? ii. What is the person s weight on the moon? iii. What is the person s mass on the moon? 3.3 I can draw properly labeled free-body diagrams that show all forces acting on an object. a) Draw and label free-body diagram for each of the following situations: i. A box in free-fall (meaning no air resistance). ii. A box being pushed across a rough surface with constant velocity. iii. A box hanging from the ceiling by a chain. 2
iv. A box orbiting Earth. 3.4 Given one force, I can describe its Newton s 3 rd Law force pair. a) A 30 N force is applied by your fist to your friend s face. State the force pair and determine the size of the force. b) A cyclist rides at 12 miles/hour before crashing into a fence with 80 N of force. State the force pair and determine the size of the force. 3.5 I can use Newton s 1 st Law to quantitatively determine the forces acting on an object moving with constant velocity. a) A person is pushing a crate full of pumpkins to the right with force of 400 N. What must the force of friction be if the crate is moving with constant velocity 6 m/s to the right? 4) Unbalanced Forces Particle Model (UBFPM) 4.1 I can relate an unbalanced force to an object s changing velocity (accelerated) motion. a) See Target 3.1 4.2 I can solve problems using Newton s 2 nd Law. a) Starting from rest, Speedy Gonzales (mass = 5 kg) reaches a top speed of 100 m/s in 2 seconds. What is the average net force exerted on Speedy? b) A 75 kg man stands on a scale inside an elevator. Sketch a free-body diagram for the man. i. When the elevator is traveling upwards with constant velocity, what will the scale read? ii. When the elevator is accelerating upwards at 2 m/s 2, what will the scale read? c) A 15 kg box is pushed with several forces in different scenarios as shown. Determine the net force (with direction) on the box and the acceleration (with direction) of the box in each scenario. 4.3 I can relate unbalanced torque to an object s rotational motion when the force is applied perpendicular to the lever arm. a) If the torque required to open a heavy door is 50.0 Nm and the force exerted by a student is 120 N, how far from the door s hinge must the student apply the force? 5) Central Net Force Particle Model (CNFPM) 5.1 I can describe and determine central net (centripetal) force and acceleration. a) Two 60 kg athletes run on a circular track. Athlete A runs on the inside lane, with radius 20 m. Athlete B runs on the outside lane, with radius 28 m. Each athlete runs at a constant speed of 6 m/s. i. Which athlete has a greater centripetal acceleration? How do you know? ii. Which athlete requires a greater centripetal force to remain on the track? iii. If the speed of the athletes were to double, how many times larger would the centripetal acceleration become (i.e. 2 times larger, 3 times larger, 4 times larger, etc.)? iv. If the mass of the athletes were to double, how many times larger would the centripetal force become? 5.2 I can explain and apply Newton s Law of Universal Gravitation. a) How would the gravitational force between two objects be affected if: i. the mass of ONE object is doubled? ii. the distance between the objects is doubled? b) If the average force of gravity between the Sun and the Earth is 60.8 x 10 21 N and the average distance is 1.5 x 10 11 m, what is the mass of the Sun? (Mass of Earth: 5.97 x 10 24 kg) c) A 150-kg astronaut is on a moon. The moon has a mass of 8.00 10 22 kg and a radius of 2.00 10 6 m. What is the weight of the astronaut on the moon? (G = 6.67 10-11 N m 2 /kg 2 ) 3
5.3 I can solve problems using Newton s 2 nd Law and the relationship between tangential velocity and centripetal acceleration. a) A ball is swung in a horizontal circle from the end of a 1.5 m long string with centripetal acceleration 5 m/s/s. What is the tangential velocity of the ball? b) A 1200 kg satellite orbits Earth with a speed of 1000 m/s. If the satellite experiences a centripetal acceleration of 9.65 m/s/s, at what altitude (distance from the center of Earth) is it orbiting? c) A roller coaster car traveling through a circular loop of radius 22 m travels at a speed of 14 m/s. If the net force on the roller coaster car is 16000 N, what is the mass of the car? 6) Vectors 6.1 I can distinguish between scalars and vectors. 6.2 I can graphically add and subtract vectors. a) A dog chases a ball 12 m North, then runs 8 m East to return the ball to his owner. What is the dog s displacement from its initial position? 6.3 I can break a 30, 45, 60, or other angle vector into components. a) A booger is flicked horizontally off a desk with a velocity of 4 m/s. Determine the x and y components of the booger s velocity. b) Another booger is flicked from the floor with a velocity of 3 m/s at an angle of 30 to the ground. Determine the x and y components of the booger s velocity. 7) Projectile Particle Model (PPM) 7.1 I can describe projectile motion using multiple representations (graphs, free-body diagrams, pictures, velocity vectors, equations, etc.) a) Sketch x-position vs. time and y-position vs. time graphs for the boogers in Target 6.3. Label the initial velocities and initial positions on each graph. 7.2 I can analyze the motion of a horizontally launched projectile. a) For the booger in Target 6.3a, determine i. the time it takes to hit the floor. Assume the desk is 0.8 m tall. ii. For the booger in Target 6.3a, determine the horizontal displacement of the booger from the edge of the desk. iii. For the booger in Target 6.3a, determine the vertical component of velocity when it hits the floor. 7.3 I can analyze the motion of a projectile launched at a 30, 45, 60, or other angle along level ground. a) For the booger in Target 6.3b, determine i. the time it takes to hit the floor. ii. the maximum height the booger reaches. iii. the total horizontal displacement of the booger. 8) Momentum Transfer Model (MTM) This model will be previewed before the midterm exam, but all targets will be officially covered 2 nd semester. Related questions on midterm exam are for pre-evaluation only and will not count towards score. 8.1 I can calculate the momentum of an object (or system of objects) including direction. a) A 2500 kg vehicle travels 22 m/s to the right. i. Calculate the momentum of the vehicle. ii. What is its momentum if travels to the left? b) A 3000 kg truck has a momentum of 54000 kgm/s. What is the truck s velocity? c) Two 1500 kg cars drive towards each other. The car traveling to the right travels 15 m/s and the car traveling to the left travels 10 m/s. What is the total momentum of the two-car system? 4
8.2 I can explain a collision or explosion scenario in words using momentum concepts including conservation of momentum, impulsive force, and Newton s 3 rd Law. a) Two ice skaters (mass A = 50 kg, mass B = 65 kg) stand facing each other, at rest, when skater A pushes skater B. Describe the velocity (magnitude and direction) of each skater after the push and explain why. b) A Jamaican bobsled team rides down an icy incline, reaching the bottom with velocity 9 m/s, then across a rough surface, eventually coming to a stop. Why wasn t their momentum conserved? c) One 0.5 kg ball collides with a second identical ball. Describe what happens to the first ball s momentum. 8.3 I can draw and analyze momentum bar charts for 1D collisions and explosions (BA or BFA charts). 8.4 I can calculate the impulse delivered to an object (or system of objects) (directly) using the relationship between the force applied and the time duration of the force as well as (indirectly) using conservation of momentum. a) A 190 kg bicycle plus rider travel at 6 m/s. The rider applies the brakes, slowing down to 3 m/s. What is the change in momentum of the bicycle plus rider? What impulse did the friction caused by braking deliver to the bicycle? b) A 2000 kg vehicle comes to rest in 0.7 s after crashing into the side of a building. During the crash, the magnitude of the acceleration of the vehicle was 0.55 m/s 2. Determine the impulse delivered to the vehicle. c) A 90 kg football player runs at 5 m/s and collides head-on and tackles another player, bringing him to rest. If the players were in contact for 1.3 seconds, how much force did each player experience? 5