text 1 psychology
On the surface of Jupiter, where the acceleration due to gravity is about three times that ofEarth, a 100-kg rock would have a mass of about
100 kg
Ten seconds after starting from rest, a freely falling object on Earth will have a speed ofabou
100 m/s
A bag of groceries has a mass of 10 kg and a weight of about
100 n
A baseball player bats a ball with a force of 1000 N. The ball exerts a reaction force againstthe bat of
1000n
The gain in speed each second for a freely falling object is about
10m/s
An apple weighs 1 N. The magnitude of net force on the apple when it is in free-fall is
1N
If aball being thrown goes from zero to 30 m/s in 1 s, what is its average acceleration
30 m/s2
On the surface of Jupiter, where the acceleration due to gravity is about three times that ofEarth, a 100-kg rock would have a weight of abou
3000 n
A man weighing 800 N stands at rest on two bathroom scales so that his weight is distributedevenly over both scales. The reading on each scale is
400 N
. weight of a person on Earth is 500 N. What is the mss
50 kg
) The weight of 0.6 kg of salami is about
6.0n
A ball tossed vertically upward rises, reaches its highest point, and then falls back to itsstarting point. During this time, the acceleration of the ball is always
directed downward.
The two measurements necessary for calculating average speed are
distance and time.
Aristotle relied on logic in explaining nature, Galileo relied on
experiment
A player catches a ball. Consider the action force to be the impact of the ball against theplayer's glove. The reaction to this force is the
force the glove exerts on the ball
When a falling object has reached its terminal velocity, its acceleration is
g
If a freely falling object were somehow equipped with an odometer to measure the distance ittravels, then the amount of distance it travels each succeeding second would be
greater than the second before
An object following a straight-line path at constant speed
has zero acceleration
If an object's mass is decreasing while a constant force is applied to the object, theacceleration
increases
One object has twice as much mass as another object, and also has twice as much
inertia
Whenever the net force on an object is zero, its acceleration
is zero
A rock is thrown vertically into the air. At the very top of its trajectory, the net force on it is
its weight
Density is the ratio of
mass to volume.
A kilogram is a measure of an object's
mass.
Where is friction most evident
on the road
A heavy rock and a light rock in free-fall have the same acceleration. The reason the heavyrock doesn't have a greater acceleration is that the
ratio of force to mass is the same
Your weight is
the gravitational attraction between you and the Earth
A light woman and a heavy man jump from an airplane at the same time and open theirsame-size parachutes at the same time. Which person will get to a state of zero acceleration first
the light woman
An object weighs 30 N on Earth. A second object weighs 30 N on the Moon. Which has thegreater mass?
the one on the Moon
A feather and a coin will have equal accelerations when falling in a vacuum because
the ratio of each object's weight to its mass is the same
When a loaf of bread rises, its density
decreases.
Whirl a rock at the end of a string and it follows a circular path. If the string breaks, thetendency of the rock is to
follow a straight-line path
Two objects of the same size but unequal weights are dropped from a tall tower. Taking airresistance into consideration, the object to hit the ground first will be
the heavier object
Neglecting friction, a large block of ice and a small block of ice start sliding down an inclinetogether. The heavier block will get to the bottom
at the same time as the light block
A huge Mack truck and a small Volkswagen traveling at the same speed have a head-on9
both cars
A skydiver jumps from a high-flying plane. As the velocity of her fall increases, theacceleratio
decrease
Which direction does a table push a book resting on it
up
A falling object that has reached its terminal velocity continues to move with constant
velocity
As an object freely falls, its
velocity increases
A ball is thrown upward and then falls the same distance back to the Earth. It takes 5 secondsto reach the maximum height. Neglecting air resistance, its total time in the air is abou
10 s
Arnold Strongman and Suzie Small each pull very hard on opposite ends of a rope in a tug-of-war. The greatest force on the rope is exerted by
both the same, interestingly enough
An object is propelled along a straight-line path by a force. If the net force were doubled, itsacceleration would
double
An elephant and a feather fall from a tree through the air to the ground below. The amount ofair-resistance force is greater on the
elephant
A player hits a ball with a bat. The action force is the impact of the bat against the ball. Thereaction to this force is the
force of the ball against the bat
When can an object be in a state of equilibrium?3
when two or more forces are acting on it and net force is zero
The force required to maintain an object at a constant velocity in free space is equal to
zero
A force of 1 N accelerates a mass of 1 kg at the rate of 1 m/s2. The acceleration of a mass of2 kg acted upon by a force of 2 N is
THE same
Action and reaction forces comprise the parts of
a single interaction
An object is in free fall. At one instant, it travels at a speed of 50 m/s. Exactly 1 s later, itsspeed is about
60 m/s.
A 10-N falling object encounters 4 N of air resistance. The magnitude of the net force on theobject is
6n
the Earth pulls on the Moon. Similarly, the Moon pulls on the Earth, evidence that
A) Earth and the Moon are simply pulling on each other.B) Earth's and the Moon's pulls comprise an action reaction pair both A and B:
The scientist to first introduce the concept of inertia was
Galileo.
Two factors that greatly affect air resistance on falling objects are the size and
Speed of the object
A jumbo jet has a mass of 100,000 kg. The thrust for each of four engines is 50,000 N. Whatis the jet's acceleration in meters per second squared when taking off?
2
A car has a mass of 1000 kg and accelerates at 2 m/s2. What is the magnitude of the forceexerted on the car?
2000 N
A 10-kg block accelerating at 2 m/s2 slides across a horizontal surface and comes to rest.The stopping force acting on the block is about
2n
A girl pulls on a 10-kg wagon with a constant force of 30 N. What is the wagon'sacceleration in meters per second squared?
3,.0
An object is pulled northward with a force of 10 N and southward with a force of 15 N. Themagnitude of the net force on the object is
5 N
The average speed of a horse that gallops a distance of 10 km in a time of 2h is
5 km/h
5 second after starting from rest, a freely falling object will have a speed of about
50 m/s
A skydiver who weighs 500 N reaches terminal velocity of 90 km/h. The air resistance on theskydiver is then
500 n
When a woman stands at rest with two feet on a scale, the scale reads 500 N. When shegently lifts one foot, the scale reads
500n
A tow truck exerts a force of 3000 N on a car, accelerating it at 2 m/s2. What is the mass ofthe car?
1500 kg
A rocket becomes progressively easier to accelerate as it travels upward from the groundmainly because
the mass of the rocket decreases as fuel is burned
A sack of potatoes weighing 200 N falls from an airplane. As the velocity of fall increases,air resistance also increases. When air resistance equals 200 N, the sack's acceleration in metersper second squared is
0
A 10-N falling object encounters 10 N of air resistance. The net force on the object is
0 N
What is the acceleration of a car that maintains a constant velocity of 100 km/h for 10 s
0 m/s
A hockey puck is set in motion across a frozen pond. If ice friction and air resistance areneglected, the force required to keep the puck sliding at constant velocity is
0 n
The mass of a pet turtle that weighs 10 N is about
1 kg
A 1-kg rock that weighs 10 N is thrown straight upward at 20 m/s. Neglecting air resistance,the net force that acts on it when it is half way to the top of its path is
10
A 1-kg mass at Earth's surface weighs about
10 N
The force of friction on a sliding object is 10 N. The applied force needed to maintain aconstant velocity is
10 N
Disregarding air drag, how fast must you toss a ball straight upward in order for the ball toremain in the air for a total time of 2 s?6
10 m/s
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
A ball is thrown upward with a speed of 50 m/s. How many seconds will it take to reach 0m/s at maximum height
5s
If a car increases its velocity from zero to 60 km/h in 10 s, its acceleration is
6 km/h ∙ s
A car accelerates from rest at 2 m/s2. What is its speed 3 s after the car starts moving?
6 m/s
Which has zero acceleration?
A) an object at rest B) an object moving at constant velocity C) an object in mechanical equilibrium D) all of the above
An object in mechanical equilibrium is an object
A) at rest. B) moving with constant velocity .C) having no acceleration .D) all of the above Answer: D
Compared with a 1-kg block of solid iron, a 2-kg block of solid iron has twice as much
A) inertia. B) mass. C) volume. D) all of the above E) none of the above Answer: D
Compared with the mass of a certain object on Earth, the mass of the same object on the Moonis
A) less. B) more. C) the same. Answer: C
A force is a vector quantity because it has both
A) magnitude and directio
The force that allows you to walk is
A) the friction force of the floor on your foot. B) the reaction force of your foot against the floor. C) both A and B
If a rocket initially at rest accelerates at a rate of 50 m/s2 for 2, its speed will be.
B) 100 m/s.
When a rock thrown straight upward gets to the exact top of its path, its velocity is
B) zero and its acceleration is about 10 m/s2
A rock is thrown vertically into the air. At the top of its path, its acceleration in meters persecond squared is
about 10
It takes 5 s for a stone to fall to the bottom of a mine shaft. How deep is the shaft?
about 125 m
A package falls off a truck that is moving at 30 m/s. Neglecting air resistance, the horizontalspeed of the package just before it hits the ground is
about 30 m/s.
If the mass of an object does not change, a constant net force on the object produces constant
acceleration
Disregarding air resistance, objects fall at constant
acceleration.
When you stand at rest on a pair of bathroom scales, the readings on the scales will always
add to equal your weight
A heavy object and a light object are dropped at the same time from rest in a vacuum. Theheavier object reaches the ground
at the same time as the lighter object
If an object falls with constant acceleration, the velocity of the object must
continually change by the same amount each second
An object is propelled along a straight-line path in space by a force. If the mass of the objectsomehow becomes twice as much, its acceleration
halves.
A sheet of paper can be withdrawn from under a container of milk without toppling it if thepaper is jerked quickly. This best demonstrates that
the milk carton has inertia
) As a ball falls, the action force is the pull of Earth's mass on the ball. The reaction force is
the pull of the ball's mass on Earth
When a squid pushes against water, the squid moves forward because
the water pushes against the squid
