HW#21 Ch 7: Kinetic Energy and Work
Instructions: Show your work by writing formulas and showing substitutions to earn full credit.
1. Chevrolet claims that its cars can accelerate from rest to 30 m/s in 8 s. The car’s mass is 1500 kg. (a) Assuming that its performance is achieved at constant power, determine the power developed by the car’s engine. (b) What is the car’s speed after 4 s, neglecting friction and air resistance?
2. An eight kilogram brick is pushed by a variable force from the point (1,0) to the point (5m,6m). Its acceleration as a function of its position is shown in the figures below, where ax is the x-component of the acceleration and ay is the y-component of the acceleration. a) If the brick starts from rest, how fast is it moving when it reaches its final destination? (b) What direction is it heading, relative to the +x axis?
3. A 1600 kg winch has a power output that varies with time as \(P\left( t \right) = \left( 405 \frac{{W}}{{s^{3/2}}} \right) {t^{3/2}}\). If it starts from rest at x = 0, what is its position as a function of time?
4. A single force acts on a 2.0 kg frozen chicken whose position is given by x = 3.0t − 4.0t2 + 1.0t3, where x is in meters and t is in seconds. Find the work done on the chicken by the force from t = 0 to t = 4.0 s.