Physics Ch 5
Friction arises from what:?
Breakages/irregularities whih are found on the surface of all solid materials
(True/ False) The acceleration produced by a net force acting on an object is directly proportional to the magnitude of the net force.
True
(True/False) A fluid can be either a liquid or gas.
True
(True/False) The combination of all the forces that act upon an object is called the net force.
True
(True/False) The name of the force that just balances the wight of a book lying at rest on a table top is called the normal force.
True.
If an object is placed on an inclined plane, the force exerted perpendicularily to the surface will tend to ___________ as the angle of the plane is increased
increase
Kinetic friction is always _________ that\as static friction
less
Any force which acts perpendicularily to a surface is referred to as a ______ force.
normal
Except under extreme parameters, friction has been found to be practically independent of the _______ of two materials in contact
surface areas
What is inversely proportional to the mass of an object?
the acceleration produced by a net force acting on an object
A force of 100 newtons accelerates a mass of 100 kg at the rate of 1 meter/sec(squared) The acceleration of an object with a mass of 2 kg acted upon by a force of 2 newtons is...
the same
Which of the following would exert the most pressure on the ground? -A woman in running shoes -A woman in high heels -A woman standing on skis
A woman standing in high heels
What is pressure defined as?
Force per area`
How does the acceleration of an object change in relation to it's mass?
Inversely proportional
If the net force acting on an object doubles, what happens to the object's acceleration?
It doubles
An object is being moved by a constant net force. Id the mass if the object is doubled, what happens to the objects acceleration?
It is reduced by one half
Compared to its weight on Earth, what will a 10 kg object on the moon weigh?
Less
What are accelerations produced by?
Net forces
The SI unit of pressure is...
Newton's per square meter
Friction is a force that always acts how?
Opposite to the object's motion
CHAPTER 5
Physics
A 767 commercial jet has the mass of 30000 kg. The thrust for each of its 4 engines is 15000 newtons. What is the jet's aceleration when taking off?
2.0 m/s (squared)
The terminal velocity for a person parachuting (with the chute open) is about what?
20 kilometers per hour
A car has a mass of 1000 kg and acceleration at 2 meters/sec(squared.) What is the magnitude of the net force acting upon the car?
2000 newtons
A girl pulls on a 10 kg wagon with a constant net force of +30 newtons. What is the wagon's acceleration?
3.0 meters/sec
A 10 Newton and a 30 newton force act simultaneously on an object in the same direction. What is the magnitude of the net force acting on an the object?
40 newtons
When a woman stands with both feet on a bathroom scale, the scale reads 500 newtons. If she were to lift one foot what would the scale then read?
500 Newtons
When an object reaches its terminal velocity, its net acceleration is...
0
An apple weighs 4 newtons. When held at rest above your head the net force acting on the apple is what?
0 Newtons
An object that weighs -10 newtons, encounters a +10 newtons of air resistance as it falls. What is the magnitude of the net force acting on the object?
0 Newtons
A block is dragged without acceleration in a straihgt line path across a level surface by a force of +6 newtons. What is the frictional force acting between the block and the surface?
-6 Newtons
An object that weighs -10 newtons encounters +4 newtons of air resistance as it falls. What is the magnitude of the net force acting on the object?
-6 Newtons
An apple weighs 1 newton. When the apple is in free fall, the net force acting on the apple is what?
1 Newton
A 10 newton force and a -30 newton force act on an object in opposite directions. What is the magnitude of the net force acting on the object?
-20 newtons
An airliner cruises at a constant velocity when the total thrust of the engines on the jet is 40000 newtons. How much is air resistance acts on the jet?
-40000
A 10 kg and 1 kg brick are both dropped simultaneously in a vacuum. What would the force of gravity on the 10 kg brick be?
10 times as much as the force on the 1 kg brick
The mass of a dog that weighs 100 newtons is about what?
100 kg
A bag of groceries has a mass of 10 kg and weighs about what?
100 newtons
A girl whose weight is 200 Newtons, hangs from a bar supported by two strands of rope. What is the tension in each strand of rope?
100N
How much force is needed to accelerate a 2 kg physics book with an acceleration of 6 m/s(squared)
12 (6 m/s =12N/2 kg)
A tow truck exerts a force of 3000 newtons on a car thereby accelerating it at 2 meters/sec(squared.) What is the mass of the car?
1500
An objects has a constant mass. A constant net force on the object produces a constant what?
Acceleration
Suppose a particle is accelerated through space by a constant +10 newton force. Suddenly, the particle encounters a second force of -10 newtons. What does the particle do?
Continues at the same velocity it had when it encountered the second force
A rock is thrown vertically into the air. At the very top of its trajectory, the net force acting on the rock is what?
Equal to its weight
Suppose the force of friction on a sliding object is 10 newtons. The force needed to maintain a constant velocity is...
Exactly 10 newtons
(True/False) A steel ball and a wooden ball of the same size are released simultaneously from the top of a tower. In the absence of air resistance, they would both reach the grounf at the same time. The reason for this is that the net force on each ball is the same.
False
(True/False) Excluding the force due to air pressure, there is only one force acting on a book lying on a table top.
False
(True/False) It is possible for an object in free fall to have a zero acceleration.
False
(True/False) The acceleration of an object is inversely proportional to the net force acting upon the object.
False
Pressure is defined as the force one object exerts on another object.
False
(True/False) The pascal is a unit of force.
False.
The speed of an object dropped in air will continue to increase without limit.
False.
A heavy person and a light person parachute together and wear the same size parachutes. Assuming they both open their parachutes at the same time, which person reaches the ground first?
The heavy person
What does Newton's second law state?
The mass of an object equals its acceleration divided by the net force acting on the object.
The reason a tennis ball and a solid steel ball will accelerate at the same rate in the absence of air resistance is because why?
The net force to mass ratio is the saame for both objects.
A tennis ball and a solid steel ball of the same size are dropped at the same time from the same height. Which ball has the greater force acting on it?
The steel ball
A tennis ball and a solid steel ball of the same size are dropped at the same time from the same height. In the absence of air resistance, which ball has the greater acceleration?
They both have the same acceleration.
A push on a 1 kg brick accelerates the brick. Neglecting friction to equally accelerate a 10 kg brick, one would have to push...?
With 10 times as much force
Does the acceleration produced by a net force avting on an object go in the same direction as the net force?
Yes
