5.7 - Interactive checkpoint: heavy cargo
A helicopter of mass 3770 kg can
create an upward lift force F. When
empty, it can accelerate straight
upward at a maximum of 1.37 m/s^2.
A careless crewman overloads the
helicopter so that it is just unable to
lift off. What is the mass of the
cargo?
Answer:mc = kg
5.8 - Interactive checkpoint: pushing a box
Len pushes toward the right on a
12.0 kg box with a force of magnitude
31.0 N. Martina applies a 11.0 N force
on the box in the opposite direction.
The magnitude of the kinetic friction
force between the box and the very
smooth floor is 4.50 N as the box
slides toward the right. What is the
box’s acceleration?
Answer:a = m/s^2
5.9 - Interactive problem: flying in formation
The simulation on the right will give you some practice with Newton’s second law.
Initially, all the space ships have the same velocity. Their pilots want all the ships to
accelerate at 5.15 m/s^2. The red ships have a mass of 1.27×10^4 kg, and the blue
ships, a mass of 1.47×10^4 kg. You need to set the amount of force supplied by the
ships’ engines so that they accelerate equally. The masses of the ships do not
change significantly as they burn fuel.
Apply Newton’s second law to calculate the engine forces needed. The simulation
uses scientific notation; you need to enter three-digit leading values. Enter your
values and press GO to start the simulation. If all the ships accelerate at 5.15 m/s^2 ,
you have succeeded. Press RESET to try again.If you have difficulty solving this problem, review Newton's second law.(^94) Copyright 2007 Kinetic Books Co. Chapter 05