Dave pushes his four-year-old son Thomas across the snow on a sled. As Dave pushes, Thomas speeds up. Which statement is true? A. The force of Dave on Thomas is larger than the force of Thomas on Dave. B. The force of Thomas on Dave is larger than the force of Dave on Thomas. C. Both forces have the same magnitude. D. It depends on how hard Dave pushes on Thomas.

Craig is trying to push a heavy crate up a wooden ramp, but the crate won't budge. The direction of the static friction force acting on the crate is
A. Up the ramp.
B. Down the ramp.
C. The friction force is zero.
D. There is not enough information to tell.

Josh and Taylor, standing face-to-face on frictionless ice, push off each other, causing each to slide backward. Josh is much bigger than Taylor. After the push, which of the two is moving faster?

Walking without slipping requires a static friction force between your feet (or footwear) and the floor. As described in this chapter, the force on your foot as you push off the floor is forward while the force exerted by your foot on the floor is backward. But what about your other foot, the one moved during a stride? What is the direction of the force on that foot as it comes into contact with the floor? Explain.

A person sits on a sloped hillside. Is it ever possible to have the static friction force on this person point down the hill? Explain.

A jet plane is speeding down the runway during takeoff. Air resistance is not negligible. Identify the forces on the jet.

A compact car has a maximum acceleration of $4.0 \mathrm { m } / \mathrm { s } ^ { 2 }$ when it carries only the driver and has a total mass of 1200 kg. What is its maximum acceleration after picking up four passengers and their luggage, adding an additional 400 kg of mass?

A car has a maximum acceleration of $5.0 \mathrm { m } / \mathrm { s } ^ { 2 }$. What will the maximum acceleration be if the car is towing another car of the same mass?

A 23 kg child goes down a straight slide inclined $38 ^ { \circ }$ above horizontal. The child is acted on by his weight, the normal force from the slide, and kinetic friction. a. Draw a free-body diagram of the child. b. How large is the normal force of the slide on the child?

Helium gas enters a steady-flow expander at 800 kPa, 300$^{\circ} \mathrm{C}$ and exits at 120 kPa. The expansion process can be considered a reversible polytropic process with exponent n = 1.3. Calculate the mass flow rate for 150-kW power output from the expander.

List the four signals in an SPI bus and describe each one.

Fod the demand equations, find the rate of change of q with respect to p. $p=100-q^{2}$

When production is very high but demand is very low, it can lead to?

The daily demand x for a certain product (in hundreds of pounds) is a random variable with the probability density function $f(x)=\frac{6}{343} x(7-x)$, [0, 7]. (a) Find the mean and standard deviation of the demand. (b) Find the median of the demand. (c) Find the probability that the demand is within one standard deviation of the mean.