Newton's 3rd Laws of Motion--Action/Reaction

When a cannon is fired, are the forces on the cannonball and on the cannon equal in magnitude? Are the accelerations of each equal?

Forces are equal, but acceleration is unequal.

How does a helicopter gets its lifting force?

Helicopter blades force air downward; reaction air force blades upward, providing lift.

If you hit a wall with a force of 200N, how much force does the wall exert on you?

200N

Consider hitting a baseball with a bat. If we call the force the bat exerts against the ball the action force, identify the reaction force.

A baseball hits a bat.

Identify the force that propels a rocket?

Exhaust gases push rocket, in reaction to rocket pushing exhaust gases.

When a hammer exerts a force on a nail, how does this amount of force compare with that of the nail on the hammer?

Both are the same.

When a cannon is fired, why do the cannonball and cannon have very different accelerations?

Equal forces on unequal masses produce unequal acceleration according to Newton's second law.

Fill in the blanks: Newton's first law is often called the law of _____; Newton's second law highlights the concepts of force, mass, and ______; and Newton's third law is the law of _____ and _____.

Inertia; acceleration; action; reaction

If a bat hits a ball with 1000N of force, can the ball exert less than 1000N of force on the bat? More than 1000N?

No, No. Reaction force always has exactly the same magnitude as action force.

Can you physically touch another person without that person touching you with the same magnitude of force?

No, touching is an interaction between two bodies

Can an action force exist without a reaction force?

No. Every force is an interaction involving a pair of forces. A single force doesn't exist.

If the world pulls you downward against your chair, what is the reaction force?

Reaction is you pulling upward on the world.

When you walk along a floor, what pushes you along?

The floor

Why don't the enormous number of interatomic forces inside a baseball accelerate the baseball?

They act within a system, so there is no net force on the system

True or False? When a net force is exerted on a system, the system will accelerate; but when an applied force and its reaction are within a system, the system as a whole does not accelerate.

True

How many horizontal forces are exerted on the horse in Figure 7.14? What is the horizontal net force on the horse?

Two, F and P; net force on the horse is F-P

How many horizontal forces are exerted on the horse-cart in Figure 7.14? What is the horizontal net force on the horse-cart system?

Two, F and f; net force is F-f

Referring to Figure 7.14 (pg. 115), how many horizontal forces are exerted on the cart? What is the horizontal net force on the cart?

Two, P and f; net force is P-f

When can two kicks on a soccer ball produce a net force of zero on the ball?

When both kicks are simultaneous, equal magnitude, and opposite in direction

State Newton's third law of motion.

When one object exerts a force on a second object, the second objects exerts an equal force in opposite direction on the first.