Chapter5
If the system is considered to be the apple and the orange together as shown in (Figure 1), identify the force that accelerates the apple-orange system.
A friction force acting on apple's feet.
When you bat a ball, does the ball react at the same time, or a bit later?
At the same time.
Rank the speeds of the airplane across the ground from fastest to slowest.
B A C
Part complete Fill in the blanks: Newton's first law is often called the law of ____; Newton's second law is the law of ____; and Newton's third law is the law of ____.
Inertia, acceleration, action -reaction
Can you push on a wall without the wall pushing back on you?
No, because your push is part of an interaction with the wall.
Can you physically touch a person without that person touching you with the same amount of force?
No, when you touch a person, they must touch you with an equal and opposite force.
Because the forces that act on a cannonball and the recoiling cannon from which it is fired are equal in magnitude, why are the accelerations of both so different?
Remember F=ma, and note that the cannon has a much greater mass than the cannonball, so the cannon accelerates less for the same force.
Why can't a boxer hit a piece of tissue paper in midair with the same amount of force with which he hits a heavy punching bag?
The boxer can only hit the tissue paper with a force as large as the tissue paper can exert on the boxer, and the low-mass tissue can only exert a weak force.
How does a helicopter get its lifting force?
The helicopter exerts downward forces on air; the reaction forces of the air on the helicopter are upward and called lift.
How does the force on the rifle compare with the force on the bullet, and why? View Available Hint(s)for Part A Hint 1for Part A. Law that relates the force of action and reaction
The magnitude of the force of the rifle is equal to the magnitude of force on the bullet and the forces are in the opposite direction, because for every action there is an equal and opposite reaction.
What happens to the magnitude of the normal vector on a block resting on an incline when the angle of the incline increases?
The magnitude of the normal vector decreases.
A small car and a large truck have a head-on collision. Which of the following statements is true? View Available Hint(s)for Part A Hint 1for Part A. What does Newton's third law say about the magnitudes of action and reaction forces?
The magnitudes of both forces are the same.
What specific force is accelerating Nellie (Figure 5.23 in the textbook) down the hill? (assume friction to be neglectable) View Available Hint(s)for Part A Hint 1for Part A. Resolve forces that are not aligned with the axes.
The x-component of the force of gravity
How many forces are required for an interaction?
Two forces, an action and a reaction, are needed for an interaction.
To produce a net force on a system, must there be an externally applied net force?
Yes, there must be an external net force on the system
Part complete Earth pulls down on you with a gravitational force that you call your weight. Do you pull up on Earth with the same amount of force?
Yes, you pull up on Earth with the same force.
Force vector components for a sled pulled horizontally by a rope at an upward angle _______.
are normally at right angles to each other
Part complete The team to win in a tug-of-war is the team that _______. View Available Hint(s)for Part A Hint 1for Part A. What forces besides pulling forces act in a tug-of-war?
pushes harder on the floor while holding the rope
Part complete The force that propels a rocket is that provided by _______. View Available Hint(s)for Part A Hint 1for Part A. Define an action-reaction pair of forces in general.
the expelled gas pushing on the rocket
Part complete A boxer cannot exert much force on a piece of tissue paper suspended in air because _______. View Available Hint(s)for Part A Hint 1for Part A. In an interaction, how are the opposite forces?
the tissue paper has too little mass to exert as much force on the boxer's fist
