Phy 2.3.4
A rock weighs 30 N on Earth. A second rock weighs 30 N on the moon. Which of the two rocks has the greater mass?
the one on the moon
Compared to the mass of a certain object on Earth, the mass of the same object on the moon is
the same.
An object is propelled along a straight-line path by a force. If the net force were doubled, the object's acceleration would be
twice as much.
While an object near the Earth's surface is in free fall, its
velocity increases.
A car maintains a constant velocity of 100 km/hr for 10 seconds. During this interval its acceleration is
zero
A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding at constant velocity is
zero
Henry Heavyweight weighs 1450 N and stands on a pair of bathroom scales so that one scale reads twice as much as the other. What are the scale readings in Newtons? Enter your answers numerically separated by a comma.
483 and 967
An object is pulled northward by a force of 10 N and at the same time another force of 15 N pulls it southward. The magnitude of the resultant force on the object is
5 N
A car takes 5.0 s to go from v = 0 m/s to v = 25m/sat constant acceleration. If you wish to find the distance traveled using the equation d=1/2at2, what value should you use for a? Please include the units
5 m/s^2
Note the reading on the scales.Burl the painter has a weight of 600N, and carries a 100-N bucket of paint. What is the weight of the scaffold
500N
A 10-N falling object encounters 4 N of air resistance. The net force on the object is
6 N
If a car increases its velocity from zero to 60 km/h in 10 seconds, its acceleration is
6 km/h/s.
Lucy Lightfoot stands with one foot on one bathroom scale and her other foot on a second bathroom scale. Each scale reads 380 N . What is her weight in Newtons?
760
A 10-kg brick and a 1-kg book are dropped in a vacuum. The force of gravity on the 10-kg brick is
10 times as much.
The force of friction on a sliding object is 10 N. The applied force needed to maintain a constant velocity is
10N
A ball is released from rest and falls for 15 seconds. How far will it travel during that time?(Assume g = 10 m/s2). Please include the standard abbreviation for the units, with a space after the number.
1125 m
A tow truck exerts a force of 3000 N on a car, accelerating it at 2 meters per second per second. What is the mass of the car?
1500 kg
Calculate the weight in newtons of a 1600-kg elephant. Express your answer to two significant figures and include the appropriate units.
16000 N
A horse gallops a distance of 10 kilometers in a time of 30 minutes. Its average speed is
20 km/h
An object at rest near the surface of a distant planet starts to fall freely. If the acceleration there is twice that of the Earth, its speed one second later would be
20 m/s
If a freely falling object were somehow equipped with a speedometer on a planet where the acceleration due to gravity is 20 m/s/s, then its speed reading would increase each second by
20 m/s
A car has a mass of 1000 kg and accelerates at 2 meters per second per second. What is the magnitude of the net force exerted on the car?
2000 N
A girl pulls on a 10-kg wagon with a constant horizontal force of 30 N. If there are no other horizontal forces, what is the wagon's acceleration in meters per second per second?
3.0
If a rocket initially at rest accelerates at a rate of 50 m/s2 for one minute, its speed will be
3000 m/s.
The force of friction on a sliding object is 10 newtons. The applied force needed to maintain a constant velocity is
10 N
An apple falls from a tree and hits the ground 5 meters below. It hits the ground with a speed of about
10 m/s
A force of 1 N accelerates a mass of 1 kg at the rate of 1 m/s2. The acceleration of a mass of 2 kg acted upon by a net force of 2 N is
The same.
Galileo's interpretation of motion differed from Aristotle's in that Galileo emphasized
Time rates
Which has zero acceleration? An object
all the these
According to Newton's law of inertia, a railroad train in motion should continue going forever even if its engine is turned off. We never observe this because railroad trains
always have forces that oppose their motion.
If a non-rotating object has no acceleration, then we can say for certain that it is
in mechanical equilibrium.
If an object's mass is decreasing while a constant force is applied to the object, the acceleration
increases
A heavy block at rest is suspended by a vertical rope. When the block is accelerated upward by the rope, the rope tension
increases.
In each second of fall, the distance a freely falling object will fall is
increasing
Whenever the net force on an object is zero, its acceleration
is zero.
A force is a vector quantity because it has both
magnitude and direction.
A kilogram is a measure of an object's
mass
In which case would you have the largest mass of gold? If your chunk of gold weighed 1 N on the
moon
Twelve seconds after starting from rest, an object falling freely will have a speed of
more than 100 m/s.
An object's weight may properly be expressed in units of
newtons
When a rocket ship accelerating in outer space runs out of fuel, it
no longer accelerates.
The maximum acceleration of a car while towing a second car twice its mass, compared to its acceleration with no car in tow, is
one third.
Galileo's use of inclined planes allowed him to effectively
reduce the acceleration of free fall.
Your weight is
the gravitational attraction force between you and the Earth.
Strange as it may seem, it is just as hard to accelerate a car on a level surface on the moon as it is here on the Earth. This is because
the mass of the car is independent of gravity.
If a freely falling object were somehow equipped with a speedometer, its speed reading would increase each second by about
10 m/s
Consider a mass of 1 kg accelerated 1 m/s/s m/s2 by a force of 1 N Find the acceleration for a force of 2 N acting on 2 kg. Express your answer to one significant figure and include the appropriate units.
1 m/s/s
A ball is tossed with enough speed straight up so that it is in the air several seconds. Assume upward direction is positive and downward is negative. What is the velocity of the ball in m/s one second BEFORE it reaches its highest point? (Assume g = 10 m/s2)
10
A ball is tossed with enough speed straight up so that it is in the air several seconds. Assume upward direction is positive and downward is negative. What is the acceleration of the ball in m/s2 when it REACHES its highest point?
-10
A ball is tossed with enough speed straight up so that it is in the air several seconds. Assume upward direction is positive and downward is negative. What is the velocity of the ball in m/s one second AFTER it reaches its highest point? (Assume g = 10 m/s2)
-10 m/s
What is the instantaneous velocity of a freely falling object 15 seconds after it is released from a position of rest? (Assume g = 10 m/s2). Assume upward is positive and downward is negative. Please include the standard abbreviation for the units, with a space after the number.
-150 m/s
Surprisingly, very few athletes can jump more than 2 feet (0.6 m) straight up. (a) Use d =1/2gt^2 and solve for the time one spends moving upward in a 0.6-m vertical jump. Then double it for the "hang time"-the time one's feet are off the ground, include two decimal places in your answer. Assume g = 10 m/s^2. Include units in your answer.
.69 seconds
A ball is tossed with enough speed straight up so that it is in the air several seconds. Assume upward direction is positive and downward is negative. What is the velocity of the ball in m/s when it reaches its highest point?
0
A 10-N falling object encounters 10 N of air resistance. The net force on the object is
0 N
An apple weighs 1 N. When held at rest above your head, the net force on the apple is
0 N
One pound is the same as 4.45 newtons. What is the weight in pounds of 1 newton?
0.225 Pounds
Calculate the acceleration of a 330000 kg jumbo jet just before takeoff when the thrust on the aircraft is 170000 N .
0.52 m/s^2
An apple at rest weighs 1 N. The net force on the apple when it is in free fall is
1 N
When you relax at rest with your left foot on one bathroom scale and your right foot on a similar scale, each of the scales will
Any of these may be correct.
The scientist to first introduce the concept of inertia was
Galileo
A bag of groceries has a mass of 10 kilograms and a weight of
about 100 N.
It takes 6 seconds for a stone to fall to the bottom of a mine shaft. How deep is the shaft?
about 180 m
A package falls off a truck that is moving at 30 m/s. Neglecting air resistance, the horizontal speed 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
Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has twice as much
all of these
If an object moves with constant acceleration, its velocity must
change by the same amount each second.
Your car is coasting on level ground at 60 km/h and you apply the brakes until the car slows to 40 km/h. If you suddenly release the brakes now, the car tends to
continue moving at 40 km/h.
If no external forces are acting on a moving object, it will
continue moving at the same velocity.
The two measurements necessary for calculating average speed are
distance and time
Whirl a rock at the end of a string and it follows a circular path. If the string breaks, the tendency of the rock is to
follow a straight-line path.
The newton is a unit of
force
If an object falling freely were somehow equipped with an odometer to measure the distance it travels, then the amount of distance it travels each succeeding second would be
greater than the second before.
An object is propelled along a straight-line path in space by a force. If the mass of the object somehow becomes twice as much, its acceleration
halves
