Physics > QUESTION PAPER & MARK SCHEME > PHYS Straighterline Review Questions and Answers, Rated A+, For help with Straighterline courses, re (All)

An amusement park game consists of throwing a quarter into a small bowl. If you win, you get to take home a giant purple stuffed elephant. The dish is on a shelf that is 0.4 m above the point where th... e quarter leaves your hand. The horizontal distance between the bowl and the place where the quarter leaves your hand is 1.8 m. Ignoring air drag, if you toss the quarter at an angle of 60°, what initial velocity is needed to bring home the giant purple stuffed elephant? - Ans-4.8 m / s If the x-component of a vector is 3 and the y-component is 4, what is the magnitude of the vector? - Ans-5 Which of the following is involved in uniform circular motion? - Ans-constant angular velocity As shown, a crate of oranges and a crate of apples, each with a different mass, are attached by a rope (with tension Toa). A second rope (To ) is attached to the crate of oranges, and the entire system is pulled with a constant acceleration a by this rope. Which of the following is true of the tensions? - Ans-Toa > To How can you calculate the magnitude of a vector using scalar products? - Ans-Multiply it by itself and take the square root. Suppose you weigh an object and the reading you get from the scale is 0.0070 kg. How many significant digits does your measurement have? - Ans-Two Consider two objects sliding down an incline without rolling. If the objects don't have the same mass, the heavier object will accelerate at a faster rate than the lighter one. - Ans-false Which of the following statements concerning friction between the surfaces of two objects is correct? - Ans-The force of friction mostly depends on the nature of the two surfaces. Calculate x=vt+1/2at2, where v = 0.227 m/s. t = 11.1s, and a = 9.80 m/s2. - Ans-606 m Which of the following statements concerning friction is incorrect? - Ans-The force of static friction ( fs ) between parallel surfaces in contact is given by: fs = μsN. A car travels with a speed of 3.5 m / s, and then accelerates to 5.5 m / s in 4 s. Which of the following is the average acceleration of the car? - Ans-0.5 m / s2 If the cross product of a vector of length 5 and a vector of length 3 results in a vector of length 10, what is the angle between them? - Ans-42° A vector is quantity that requires both magnitude and ________. - Ans-direction King Kong is holding a woman on top of a skyscraper when she suddenly slips out of his hand. How tall is the building if Superman has a minimum time of 2.30 s to catch the woman before she hits the ground? - Ans-25.9 m Kylie throws Kyra a kiwi. The kiwi leaves Kylie's hand at a height of 1.3 m from the ground and Kyra grabs it out of the air at a height of 1.6 m. Kylie throws the kiwi at an angle of 33° relative to the horizontal. The kiwi is in the air for 1.1 s. How far apart are Kylie and Kyra standing? (Assume there is no drag force that no wind is blowing.) - Ans-9.6 m A projectile is launched from a height of 250 m with initial horizontal velocity of 50 m/s. What is the horizontal range of the projectile? - Ans-357 m Imagine that you push down on an object that is sitting on a frictionless table. Which of the following diagrams includes all the forces acting on the object? - Ans-F W down, N up Your cat chases a spider across the floor. Its position is a function of time is r + (1.2m/s)ti + (0.7m + (0.5m/s2)t2)j, where the origin is the southwest corner of the floor. Find the average speed of the cat between t = 0.0s and t = 4.0s - Ans-2.3 m/s The position of an object along the x-axis is described by the formula x = 3t 2 − 2t. Which of the following are the correct formulas for the velocity and acceleration of the object? - Ans-v = 6t − 2, a = 6 Using the conversion factor between kilograms and pounds, 1 kg = 2.205 lb, calculate how many pounds are in 2.00 kg. - Ans-4.41 lb An experimental new ride at an amusement park begins by spinning patrons about a circle of radius R with constant speed v. At some point during the ride the speed doubles and the spokes extend, doubling the radius. After this occurs, what is the acceleration of the patrons in terms of the original acceleration, a ? - Ans-2a Consider a mass of 85kg lying on the ground. The coefficient of static friction between them is us = 0.65. What is the minimum force you need to apply in order to slide the mass? - Ans-541 N When turning around a circle, a car is subject to a continuous force, but its speed does not necessarily change. Why is this true? - Ans-The speed is not changing, but the direction is. A small mass is placed on a turntable that is rotating at 45 rpm. The centripetal acceleration is ____________. - Ans-greater when the mass is farther from the center of the circle How many significant figures are in the quantity 9.86 m/s 2? - Ans-3 Laura is listening to a record spinning at 45 rpm (revolutions per minute). When she switches the speed selector on the record player to 33 rpm, it takes 2.7 seconds for the record player to change to the new speed. How many revolutions does the record make during this time? Assume that the angular acceleration of the record is constant. - Ans-1.8 A 309 g glass rolls down an incline and onto a horizontal platform where it hits a beverage can that is laying at rest on its side. The top of the incline is 11.0 cm above the horizontal platform. The beverage can is initially at rest and weighs 7.35 N. Which of following is the final velocity of the glass? - Ans-−0.612 m / s This hourglass-shaped object is hung from a pivot point (round dot). Its center of gravity is marked by a cross. If the object is free to rotate, what does it do? - Ans-It does not move. You are sparring in karate class. Your opponent, standing directly in front of you, throws a punch straight into your chest. What stance will best allow you to take this punch without losing your balance? - Ans-left forward A 0.500 kg steel ball is dropped from a height of 4.00 m onto a horizontal steel slab. The collision appears elastic in that the ball rebounds to its original height. If the collision lasts for 2.00 × 10−3 s, which of the following is the impulse imparted to the ball and the average force applied to the ball during the collision? - Ans-I = 8.85 kg•m / s F = 4.43 × 103 N A spaceship is in space and currently at rest. The directive is given to accelerate from rest to a speed of 2.90 × 103 m / s. If the fuel budgeted for this action is 400 kg, which of the following is velocity of the exhaust gas required if the ship mass is 7.38 × 103 kg? - Ans--5.5 × 104 [m / s] A boat pulls a water skier who weighs 127 lbs at a constant speed. The tension in the ski rope is 125 N. The skier makes a run that is 0.7 km down a long straight river. What is the work done by the water skier on the boat? - Ans-−8.75 × 104 N • m Which of the following is the general definition of impulse ? - Ans-I = squiqqle E Fdt A pendulum bob has mass of 0.750 kg and is on a pendulum arm of length 1.00 m. The pendulum is pulled back so that the arm makes an angle of 60.0° from the vertical and is then released. Which of the following is the speed of the mass when it reaches its lowest point? - Ans-3.13 m/s An automobile of mass 900 kg is moving at a speed of 12.5 m/s when it encounters a hill. At the bottom of the hill the car speed increases to 14.6 m/s. If the elevation of the hill is 15.3 m, how much work did the brakes do while going down the hill? - Ans--1.09x105 J In a game of marbles, a 60 g marble is rolling at 8.00 cm / s when it collides with a stationary marble. the 60 g marble takes off at a 27° angle at a reduced speed of 4.89 cm / s. The second marble moves at a rate of 3.21 cm / s at a 31.7° angle. Which of the following is the mass of the second marble? - Ans-0.0800 kg Which of the following is not a unit of power? - Ans-Watt / second A freight train is traveling at a speed so that the angular velocity of its wheels is 38 rad / s. The engineer decides to accelerate the train to a speed 1.5 times faster than before. If the acceleration of the train corresponds to an angular acceleration of 0.80 rad / s2, how long does it take for the train to reach its new speed? - Ans-24 s Which of the following is a form of Hooke's law, where Fs is a spring force? - Ans-Fs = -kx Which of the following objects has the greatest kinetic energy? - Ans-an object of mass 2m and speed 3v Cats have amazing control over their bodies. If you hold a cat upside down a moderate height off the floor and drop it, it manages to right itself in midair and land on its feet. Isn't this a violation of the conservation of angular momentum? After all, the cat starts upside down, and then it somehow rotates until it is right-side up. Which of the following is the most plausible explanation for this phenomenon? - Ans-By manipulating its body, a cat can control the moment of inertia of different parts of its body in such a way that it can reorient itself in midair despite the fact that its angular momentum is zero the whole time. Which of the following is not a vector quantity? - Ans-power Tom and Joe are trying to fly a new style of kite that they have invented. Both of them are holding strings attached to the kite. The tension in each string is 126 N. The angle between the strings is 36°. Unfortunately, the kite will not rise in the air, and the strings held by Tom and Joe are essentially parallel to the ground. Tom and Joe have run a distance of 100 m trying to get the kite to fly. How much work have they done on the kite? - Ans-24,000 N • m A car is decelerating from 60 mph to 0 mph in 122 ft. If the tires have a diameter of 18 in., how many revolutions do the wheels make during the deceleration? - Ans-25.9 revolutions This diagram illustrates a water molecule (H2O). The oxygen atom has a mass of roughly 16 units, and the hydrogen atoms each have a mass of roughly 1 unit. The distance between the oxygen and hydrogen nuclei is 0.96 angstroms (an angstrom, denoted Å, is equal to 10−10 m). If the oxygen atom is located at y = 0, where is the vertical position of the center of mass of the molecule? Assume that hydrogen atoms lie towards positive y. - Ans-0.063 Å A force is applied to an object as shown. What is the direction of the torque vector? - Ans-into the screen The integral (squiggle)dt is called the angular impulse. It is equal to - Ans-the change in angular momentum A truck weighing 1000 N moves at 5.89 m / s when it has an elastic collision with another vehicle. The second vehicle, weighing 981 N, was stationary but free to move. Which of the following is the final velocity of the first vehicle after the collision? - Ans-v1 f = 0.0565 m / s Which of the following statements concerning an object in free fall through the atmosphere is incorrect? - Ans-The speed of a falling object increases due to the frictional force of air drag. Which of the following is not an example of a vector? - Ans-mass If two objects with the same radius, one with I1 = I and the other with I2 = 2I, both roll down an incline, which would reach the ground first? - Ans-The object with I1 = I. A train is on an incline and has a mass of 2.36 × 103 kg. It initially coasts at 27.8 m/s. Which of the following is the speed of the train at position B. Assume no additional assistance from the engine. - Ans-34.2 m/s A point mass m is hung on an ideal, massless rod of length z. A torque of magnitude r is applied to the system about P, displacing it as shown. What is the horizontal displacement L of the mass from vertical? - Ans-r/mg A stunt man is sliding down the side of a mountain when he manages to catch a tree with a wristwatch winch, which supplies a constant tension, T. Neglecting air friction, if the mountain slope is inclined at an angle θ, what is the acceleration of the stuntman? - Ans--T / m + g sin θ Given the vector A as shown in the figure, select the choice that gives the vector's correct description in component form. - Ans-Ax = Acos0 Ay = Asin0 [Show More]

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