Physics HW 4 - Homework 4 questions with work and answer PDF

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Homework 4 questions with work and answer...

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Problem 1: A rocket sled comes to rest in 1.2 s from a speed of 950 km/h. Assume the rocket moves in the positive direction.

What is the acceleration of the rocket sled, in meters per second squared? Numeric: A numeric value is expected and not an expression. a = __________________________________________ Problem 2: A powerful motorcycle can produce an acceleration of 3.7 m/s2 while traveling at 90 km/h. At that speed the forces resisting motion, including friction and air resistance, total 400 N. (Air resistance is analogous to air friction. It always opposes the motion of an object.) Randomized Variables: a = 3.7 m/s2 m = 275 kg

What is the magnitude of the force which the motorcycle exerts backward on the ground to produce its acceleration if the mass of the motorcycle with rider is 275 kg? Numeric: A numeric value is expected and not an expression. |F| = __________________________________________

Problem 3: A farmer is using a rope and pulley to lift a bucket of water from the bottom of a well. The farmer uses a force F1 = 50.5 N to pull the bucket of water upwards at a constant speed. The bucket, when empty, has a mass of mb = 1.2 kg. Part (a) Identify the correct Free Body Diagram for this situation. Fgw is the weight of the water and Fgb is the weight of the empty bucket. (Note that the force vectors are not necessarily drawn to scale.)

Part (b) Calculate the mass of the water in the bucket, mw in kg. Numeric: A numeric value is expected and not an expression. mw = __________________________________________

Part (c) Calculate the volume of the water in the bucket, Vw in cm3. Assume the density of the water, ρw, is 1.00 g/cm3. Numeric: A numeric value is expected and not an expression. Vw = __________________________________________

Problem 4: A freight train consists of two 8.5 • 104 kg engines and 45 cars with average masses of 5.5 • 104 kg each.

m = 8.5 • 104 kg m2 = 5.5 • 104 kg f = 7.55 • 105 N

Part (a) What is the magnitude of the force must each engine exert backward on the track to accelerate the train at a rate of 5.00 • 10–2 m/s2 if the force of friction is 7.55 • 105 N, assuming the engines exert identical forces? This is not a large frictional force for such a massive system. Rolling friction for trains is small, and consequently trains are very energy-efficient transportation systems. Numeric: A numeric value is expected and not an expression. F = __________________________________________

Part (b) What is the force in the coupling between the 37th and 38th cars (this is the force each exerts on the other), assuming all cars have the same mass and that friction is evenly distributed among all of the cars and engines? Numeric: A numeric value is expected and not an expression. F' = __________________________________________...