PH 104 Exam 1 Study Guide
A 3000N bear grasping a vertical tree slides down at constant velocity. The friction force between the tree and the bear is
3000N
You are trying to decide whether to jump off a cliff into the water below. In order to determine the height of the cliff, you drop a rock and time its fall. You find that it takes 3s for the rock to hit the water. How high must the cliff be?
45m
When you step on your brakes, your car experiences a (negative) acceleration of 6m/s^2. If you are traveling 24m/s (about 55mph). how long will it take to come to a complete stop?
4s
A person attracted toward the center of Earth by a 500N gravitational force. The Earth is attracted toward the person with a force of
500N
The force of gravity acting on a 500-newton woman standing on the earth's surface is
500N
If a person accelerates at 9 gees (9xg=90m/s^2), she may black out due to lack of blood to the brain. What force exerted on a 70-kg fighter pilot would produce a 9 gee acceleration?
6,300N
A 10N falling object encounters 4N of air resistance. The magnitude of the net force on the object is
6N
At the 2012 Olympic Games, David Rudisha of Kenya, ran the 800-meter run in a world record 1 minute and 40.91 seconds. His average speed was
7.93m/s
Which diagram below correctly shows how you draw a diagram to find F=F1+F2 using the head-to-tail method?
A. F is the hypotenuse, F1 is the bottom, F2 is the right
If I exert a constant force on an object, then I will produce
a constant acceleration
Isaac Newton knew the moon moved in a curved path around the earth, from this he could conclude that
a force must be exerted on the moon
In science, a theory is
a synthesis of a large body of well-tested knowledge
Which of the following is a vector?
all of the above
Block A has a mass of 5kg and Block B has a weight of 50N. Which is true?
block A and Block B weigh the same
Mass is a measure of
both A&B
If no external forces are acting on a moving object, it will
continue moving at the same velocity
Suppose a particle is being accelerated through space by a 10N force. Suddenly the particle encounters a second force of 10N in the opposite direction from the first force. The particle with both forces acting on it
continues at exactly speed it had when it encountered the second force
If you make a left turn in your car while keeping the same speed, then your velocity will be
different
The force of friction on a sliding object is 20N. In order to make the object move at constant velocity, you must apply a force that is
exactly 20N
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
The process of coming up with a hypothesis that explains a set of observations is called
induction
If one object has twice as much mass as another object, it also has twice as much
inertia
Which of the following is not something we desire in scientific hypothesis?
it must contain mathematical formulas
All of the following are contact forces except for
magnetic forces
A kilogram is a measure of an object's
mass
An object is thrown straight upward. While it is in flight, its acceleration will be zero
never
Two factors that greatly affect air resistance on falling objects are the
size and speed of the object
As you are driving down the highway at 25m/s, a raindrop splashes onto your windshield. Which of the following is different for the raindrop and your car?
the acceleration
Your weight is
the gravitational attraction force between you and the Earth
A skydiver falls toward the earth. The attraction of the earth pulls the skydiver down. By Newton's Third Law, we know that
the skydiver must pull the earth up
The bottom of a pail of water exerts a normal force on the water. By Newton's 3rd Law, we know that
the water must exert a force on the bottom of the pail
The synthesis of a large collection of information that contains well-tested and verified hypotheses about certain aspects of the world is known as a scientific
theory
An object if propelled along a straight-line path by a force. If the net force were doubled, the object acceleration would be
twice as much
When an object is freely falling, (I.e. no air resistance), its
velocity increases continuously as it falls
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
When a falling object has reached its terminal velocity, its acceleration is
zero