Chapter 6: Problem 27
What's the kinetic energy of a \(2.4 \times 10^{5}-\mathrm{kg}\) airplane cruising at \(900 \mathrm{km} / \mathrm{h} ?\)
/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none}
Learning Materials
Features
Discover
Chapter 6: Problem 27
What's the kinetic energy of a \(2.4 \times 10^{5}-\mathrm{kg}\) airplane cruising at \(900 \mathrm{km} / \mathrm{h} ?\)
All the tools & learning materials you need for study success - in one app.
Get started for free
Which consumes more energy, a 1.2 -k \(\mathrm{W}\) hair dryer used for 10 min or a \(7-W\) night-light left on for 24 h?
You want to raise a piano a given height using a ramp. With a fixed, nonzero coefficient of friction, will you have to do more work if the ramp is steeper or more gradual? Explain.
A typical bumblebee has mass 0.25 mg. It beats its wings 100 times per second, and the wings undergo an average displacement of about \(1.5 \mathrm{mm}\). When the bee is hovering over a flower, the average force between wings and air must support the bee's weight. Estimate the average power the bee expends in hovering.
A machine delivers power at a decreasing rate \(P=P_{0} t_{0}^{2} /\left(t+t_{0}\right)^{2}\) where \(P_{0}\) and \(t_{0}\) are constants. The machine starts at \(t=0\) and runs forever. Show that it nevertheless does only a finite amount of work, equal to \(P_{0} t_{0}\).
(a) Find the scalar product of the vectors \(a \hat{\imath}+b \hat{\jmath}\) and \(b \hat{\imath}-a \hat{\jmath}\) where \(a\) and \(b\) are arbitrary constants. (b) What's the angle between the two vectors?
What do you think about this solution?
We value your feedback to improve our textbook solutions.