Chapter 7 along with other quizlet

Two ppl have a tug of war on low friction ice. One person has 3 times the mass of the other. Compared to the lighter person, how many times does the heavier person accelerate?

1/3 times

t/f in order to make a cart move forawrd, a horse must pull harder on the cart than the cart pulls on the horse.

False

If you push off the ground with a force of 350 N when you jump upward, what force pushes Earth downward?

350 N

As a 500N woman sits on the floor, the floor exerts a force on her of

500 N

What engine thrust (in Newtons) is required for a rocket of mass 70kg to leave the launching pad?

70x10 700 N

If you exert a 10,000N on a 1000kg car and a 3000 kg truck that are both originally ay rest, what will the resulting accelerations of the objects?

Car: a=10,000 N/1000 kg Car's acceleration = 10m/s2 truck: A=10,000N/3000kg trucks acceleration=3.33 m/s2

A force is a push or a pull. Newton's third law further defines the meaning of force. Explain.

Newton's third law explains that a force is not just a single push or pull, but that there is an action force and reaction force because in an interaction one object exerts a force on another and the second object exerts an equal and opposite force on the first object.

Apply Newton's third law to a falling boulder, identifying the action and reaction forces. If a force is exerted on the earth, why doesn't it move? Explain.

Newton's third law states that whenever one object exerts a force on a second object, the second object always exerts the same amount of force back on the first object. In the situation of a boulder falling to earth, the action force is the boulder exerts a force on the earth. The reaction force is the earth exerts a force on the boulder. The forces of the falling rock and the earth are equal and opposite but they accelerate differently because of their masses. Newton's 2nd law says mass and acceleration are inversely proportional. Because the mass of the earth is so huge compared to the small mass of the boulder, we don't sense it's extermely small acceleration.

Apply Newton's third law to a falling boulder, identifying the action and reaction forces. If a force is exerted on Earth, why doesn't it move? Explain.

The action force is the boulder pushing on earth. Newton's third law states there must be an equal force in the opposite direction so the reaction force is the Earth pushing on the boulder. Because they are different masses they accelerate differently. The earth has such a bigger mass than the boulder, so the earth doesn't move.

Explain how Newton's third law applies to a cannon launching a cannonball. Which has the larger acceleration, the cannonball or the cannon? What if the cannonball were just as massive as the cannon—how fast would the cannon move compared to the cannonball?

The cannon applies force to the cannonball and in return the cannonball exerts a force on the cannon, making them an action-reaction pair. The cannonball has the greater acceleration because it has the smaller mass. If they had equal mass, they would move at the same rate.

Consider the horizontal forces acting on a horse pulling a cart. Consider forces on the cart as well as on the horse. In terms of these forces, explain why the cart moves. Explain why the horse moves. Why don't action-reaction forces cancel each other?

When a horse is pulling a cart, the cart and horse are both exerting equal forces on each other. Because of this, the forces should cancel out and the cart shouldn't move. But because the cart and horse are both exerting forces on the ground and therefore have net forces that don't cancel out so the cart moves. Action and reaction forces do not cancel out when either of the forces is external to the system being considered.

A 50kg person on in-line skates pushed against a wall with a force of 20 N and recoils. What acceleration does that person experience?

a=20N/50kg 0.4 m/s2

A fighter punches a sheet of paper in midair, and brings it from rest up to a speed of 60 m/s in 0.03 secs. What is the force of impact if the mass of the paper is 0.02 kg?

a=60 m/s/0.03 F=am F=2000 x 0.02 = 40N

Suppose you accidentally drive into a tree. The result is that the car the tree mutually exert different and opposite forces on each other.

false

T/F A bicycle and a parked car have a head-on collision. The Force of the impact is greater on the bicycle

false

a karate chop delivers a blow of 200 N to a board that breaks. The force that acts on the hand during this feat is more than 2000N

false

t/f Nellie Newton holds an apple in her hand. If action is earth pulling on the apple, than the reaction is her hand pushing up on the apple

false

t/f a given force exerted on a large mass produces a greater acceleration than the same force exerted on a small mass

false

t/f two people pull on a rope in a tug of war. Each pulls with 200 N of force. The tension in the rope is 400 N.

false

An unfortunate bug splatters against the windshield of a moving car. Compared to the deceleration of the car, the deceleration of the bug is

larger

A high school student hits a nail with a hammer. During the collision, there is a force...

on the nail and also the hammer

A player catches a ball. Consider the action force to be the impact of the ball against the player's glove. What is the reaction to this force?

the force the glove exerts on the ball

As a ball falls, the action force is the pull of Earth's mass on the ball. What is the reaction to this force?

the pull of the ball's mass on earth

A large car and a small car traveling at the same speed have a head on collision. The vehicle to undergo the greater change in velocity will be

the smaller car

A pair of blocks, one 3 times as massive as the other, are connected by a compressed spring. When the spring is released, the blocks fly apart. SOmpared to the heavier block, how many times as fast does the lighter block accelerate?

three times as fast

T/F If a train is pulling a caboose, the caboose will move if the train exerts a force on the ground that is greater than the force that the caboose exerts on the train

true

T/F forces always occur in pairs

true

T/F? A rocket is able to accelerate in the vacuum of space when it fires its engines. The force that propels the rocket is the force of the exhaust gases in the rocket

true

a rocketship is pushed forward by gases that are forced out the back of the ship.

true

t/f Earth pulls on the moon, and similarily the moon pulls on Earth. This is evidence that -earth and the moon are simply pulling on eachother -earth's and moon's pulls comprise an action-reaction pair

true

t/f whenever an object exerts a force on a nother object, the second object exerts a force of the same magnitude, but in the opposit direction to that of the first object.

true

t/f you drive past a farm and you see a cow pulling a plow to till a field. You have just learned about newtons third law, and you wonder how the cow is able to move forward if the plow is exerting an equal and opposite force on the cow. You ask your smart little sister and she answers: "The cow and plow move b/c the force exerted by the cow on the plow is smaller than the force that the cow exerys on the ground to move forward. Is her answer true or false?

true

If a horse pulls on a wagon at rest, the wagon pulls back equally on the horse. Can the wagon be set into motion?

yes, b/c there is a net force acting on the wagon