A test
A book weighs 4 N. When held at rest in your hands, the net force on the book is
0 N
When an object reaches terminal velocity its acceleration is
0 m/s²
Two people pull on a rope in a tug-of-war. Each pulls with 400 N of force. What is the tension in the rope?
400N
Suppose the force of friction on a sliding object is 42 N. The force needed to maintain a constant velocity is
42N
Free-body diagram
A diagram showing all the forces acting on an object
Interaction
A mutual action between one object and another
Netwon's 2nd Law
F=ma
True or False: All forces that are equal and opposite are considered action-reaction pairs.
False
Newton's 3rd Law
For every action there is an equal and opposite reaction
Air resistance
Friction, or drag, that acts on something moving through air
Fluids
Liquids and Gases
A person driving a car crashes into a pole. The effect is the person flies forward. This is an example of
Newtons 1st Law
Pressure
The amount of force applied to a particular area
The reason a tennis ball and a solid steel ball will accelerate at the same rate, in the absence of air resistance, is that
The reason a tennis ball and a solid steel ball will accelerate at the same rate, in the absence of air resistance, is that
Terminal Speed
The speed at which the acceleration of a falling object is zero
A tennis ball and a solid steel ball with the same diameter are dropped at the same time. Which ball has the greater force acting on it?
The steel ball
Surface Area
both pressure and air resistance depend on this
If you exert 12 N on a 3 kg car and a 6 kg truck that are both originally at rest, what will be the resulting accelerations of the objects?
car at 4 m/s/s; truck at 2 m/s/s
A force of 4 N accelerates a mass of 4 kg at the rate of 1 m/s/s. The acceleration of a mass of 8 kg acted upon by a force of 8 N is
continues at the speed it had when it encountered the force
Pressure is defined as
force per area
Accelerations are produced by
forces
on the nail and also on the hammer
larger
If a truck has ten times the mass of a car and the two vehicles are pushed with an equal force, you would expect the acceleration of the truck to be
1/10 times that of the car
Suppose a cart is being moved by a force. If suddenly a load is dumped into the cart so that the cart's mass doubles, what happens to the cart's acceleration?
1/2 as much
A sportscar has a mass of 2000 kg and accelerates at 5 m/s². What is the magnitude of the force acting on the sportscar?
10000N
A 20-N falling object encounters 8-N of air resistance. The magnitude of the net force on the object is
12N
An book weighs 15 N. The net force on the book when it is in free fall is
15 N
A boxer punches a bag with 1500 N of force. What force does the bag exert on the boxer's hand?
1500N
When a woman stands on one foot on a scale. The scale reads 295 N. When she puts her other foot down on the scale, the scale reads
295N
A jet has a mass of 40,000 kg. Each engine has a thrust of 20,000 N. There are 6 engines. What is the jet's acceleration when taking off?
3 m/s²
An ATV pulls a 25 kg log with 300 N of force. There is 200 N of friction. What is the acceleration?
4 m/s/s
A girl pulls on a 10-kg wagon with a constant force of 40 N. What is the wagon's acceleration?
4 m/s²
A jumbo jet cruises at a constant velocity when the total thrust of the engines on the jet is 40,000 N. How much air resistance acts on the jet?
40,000N
A 600-N woman sits on the floor, the floor exerts a force on her of
600N
You pull horizontally on a 50-kg crate with a force of 600 N and the friction force on the crate is 250 N. The acceleration of the crate is
7 m/s²
A tow truck exerts a force of 1500 N on a car, accelerating at 2 m/s/s. What is the mass of the car?
750 kg
all of the above are examples of equilibrium
A) in order for the car to move, a force must be exerted by you on the car's windshield B) in order for the car to move, a force must be exerted by the car's windshield on you C) in order for the car to move, an outside force must be exerted on the car D) in order for the car to move, a force must be exerted by the car on the ground
Which of the following does NOT effect air resistance?
Weight
Inversely
When two values change in opposite directions, so that if one increases the other decreases
When an object is in equilibrium it is
all of the above are examples of equilibrium
Nellie Newton holds an apple in her hand. If action is Earth pulling on the apple, then reaction is
apple pulling the earth
You are on a frozen pond, and the ice starts to crack. If you lie down on the ice and begin to crawl, this will
decrease the pressure on the ice
A care package falls from a high-flying stationary helicopter. There is air resistance. The package's velocity increases and its acceleration
decreases
When the angle of an incline with a block resting on it increases, the normal support force
decreases
How does acceleration of an object change in relation to its mass? It is
inversely proportional
A rock is thrown vertically into the air. At the very top of its trajectory the net force on it is
its weight
The unit of pressure is
newtons per square meter (or pascals)
A force is exerted on the tires of a car to accelerate the car along the road. The force is exerted by the
of the exhaust gases on the rocket
A high school student hits a nail with a hammer. During the collision, there is a force
on the nail and also on the hammer
A force is exerted on the tires of a car to accelerate the car along the road. The force is exerted by the
road
Which of the following does friction NOT depend on?
surface area
You drive past a farm and you see a cow pulling a plow to till a field. You have just learned about Newton's 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. Which of the following explains the movement of the cow and plow?
the force exerted by the cow on the plow is smaller than the force that the cow exerts on the ground to move forward
A player hits a ball with a bat. The action force is the impact of the bat against the ball. What is the reaction to this force?
the force of the ball against the bat
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
Why is the bed of nails (relatively) safe?
the nails are close together, increasing surface area
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 the earth
A force of 4 N accelerates a mass of 4 kg at the rate of 1 m/s/s. The acceleration of a mass of 8 kg acted upon by a force of 8 N is
the same
A care package falls from a high-flying stationary helicopter. There is air resistance. The package's velocity increases and its acceleration
the skydiver decelerates, but the camera-man does not
A tennis ball and a solid steel ball with the same diameter are dropped at the same time. In the absence of air resistance, which ball has the greater acceleration?
they both have the same acceleration
If the force acting on a cart triples, what happens to the cart's acceleration?
triples