The mass of a sports car is 1 200 kg. The shape of the body is such that the aerodynamic drag coefficient is 0.250 and the frontal area is 2.20 \(m^2\). Ignoring all other sources of friction, calculate the initial acceleration the car has if it has been traveling at 100 km/h and is now shifted into neutral and allowed to coast.
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Textbook Solutions for Physics for Scientists and Engineer with Modern Physics
Question
Assume the resistive force acting on a speed skater is proportional to the square of the skater's speed v and is given by f = \(-k m v^2\), where k is a constant and m is the skater's mass. The skater crosses the finish line of a straight-line race with speed \(v_i\) and then slows down by coasting on his skates. Show that the skater's speed at any time t after crossing the finish line is v(t) = \(v_i /\left(1+k t v_i\right)\).
Solution
The first step in solving 6.4 problem number trying to solve the problem we have to refer to the textbook question: Assume the resistive force acting on a speed skater is proportional to the square of the skater's speed v and is given by f = \(-k m v^2\), where k is a constant and m is the skater's mass. The skater crosses the finish line of a straight-line race with speed \(v_i\) and then slows down by coasting on his skates. Show that the skater's speed at any time t after crossing the finish line is v(t) = \(v_i /\left(1+k t v_i\right)\).
From the textbook chapter Motion in the Presence of Resistive Forces you will find a few key concepts needed to solve this.
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