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The following physics responses are provided by a student and, as such, should be considered in that context. While every effort is made for accuracy, absolute correctness cannot be fully guaranteed.
| C | I | Question | Answer |
|---|---|---|---|
| 11 | An inventor develops a stationary cycling device by which an individual, while pedaling, can convert all of the energy expended into heat for warming water. How much mechanical energy is required to increase the temperature of 300 g of water (enough for 1 cup of coffee) from 20°C to 95°C? (1 cal = 4.186 J, the specific heat of water is 4 186 J/kg×°C) | 94000 J | |
| 4 | It is late and Carlos is sliding down a rope from his third-floor window to meet his friend Juan. As he slides down the rope faster and faster, he becomes frightened and grabs harder on the rope, increasing the tension in the rope. As soon as the upward tension in the rope becomes equal to his weight: | Carlos will continue down at a constant velocity. | |
| 6 | Neglecting gravity, doubling the exhaust velocity from a single stage rocket initially at rest changes the final velocity attainable by what factor? Assume all other variables, such as the mass of the rocket and the mass of the fuel, do not change. | The final velocity doubles. | |
| 8 | A bus is designed to draw its power from a rotating flywheel that is brought up to its maximum speed (3 000 rpm) by an electric motor. The flywheel is a solid cylinder of mass 500 kg and radius 0.500 m (Icylinder = MR^2/2). If the bus requires an average power of 10.0 kW, how long will the flywheel rotate? | 308 s | |
| 11 | Heat flow occurs between two bodies in thermal contact when they differ in what property? | temperature | |
| 4 | Three identical 6.0-kg cubes are placed on a horizontal frictionless surface in contact with one another. The cubes are lined up from left to right and a force is applied to the left side of the left cube causing all three cubes to accelerate to the right at 2.0 m/s2. What is the magnitude of the force exerted on the middle cube by the left cube in this case? | 24N | |
| 6 | A uranium nucleus (mass 238 units) at rest decays into a helium nucleus (mass 4.0 units) and a thorium nucleus (mass 234 units). If the speed of the helium nucleus is 6.0*10^5 m/s, what is the speed of the thorium nucleus? | 1.0*10^4 m/s | |
| 8 | A hoop of radius 1.0 m is placed in the first quadrant of an xy-coordinate system with its rim touching both the x-axis and the y-axis. What are the coordinates of its center of gravity? | (1.0, 1.0) m | |
| 11 | The filament temperature of a light bulb is 2 000 K when the bulb delivers 40 W of power. If its emissivity remains constant, what power is delivered when the filament temperature is 2 500 K? | 98 W | |
| 4 | Three identical 6.0-kg cubes are placed on a horizontal frictionless surface in contact with one another. The cubes are lined up from left to right and a force is applied to the left side of the left cube causing all three cubes to accelerate to the right at 2.0 m/s2. What is the magnitude of the force exerted on the right cube by the middle cube in this case? | 12N | |
| 6 | During a snowball fight two balls with masses of 0.4 and 0.6 kg, respectively, are thrown in such a manner that they meet head-on and combine to form a single mass. The magnitude of initial velocity for each is 15 m/s. What is the speed of the 1.0-kg mass immediately after collision? | 3 m/s | |
| 8 | A gyroscope has a moment of inertia of 0.140 kg*m^2 and has an initial angular speed of 15.0 rad/s. If a lubricant is applied to the bearings of the gyroscope so that frictional torque is reduced to 2.00*10-2 N*m, then in what time interval will the gyroscope coast from 15.0 rad/s to zero? | 105s | |
| 11 | Consider two different rods. The greatest thermal conductivity will be in the rod with: | electrons that are free to move from atom to atom. | |
| 4 | A sled weighs 100 N. It is held in place on a frictionless 20° slope by a rope attached to a stake at the top; the rope is parallel to the slope. What is the normal force of the slope acting on the sled? | 94N | |
| 6 | A car wash nozzle directs a steady stream of water at 1.5 kg/s, with a speed of 30 m/s, against a car window. What force does the water exert on the glass? Assume the water does not splash back. | 45 N |