Physics Final 1 Flashcards
Using the standard physical meanings of the quantities t, x, v, and a, choose which of the following equations are dimensionally consistent.
Consistent V^2 = 2ax
Not Consistent v=at^2/2
Not Consistent t=a/v
Not consistent x= v/2a
Is it possible for a car to circle a race track at constant velocity?
No
Can the car circle the track at constant speed?
Yes
An object that is accelerating must have a nonzero average velocity.
False
An object with a nonzero velocity can have an acceleration of zero.
True
An object with a nonzero acceleration at some instant of time can have a velocity of zero at that instant.
True
A ball is dropped from rest. After T seconds, the ball has fallen a distance d. Relative to this location, how much farther does it fall after another 4T seconds?
24D
The magnitude of the sum of two vectors is always greater than the magnitude of either vector.
False
It is possible for a component of a vector to be zero if the vector itself is not zero.
True
It is possible for a vector to be zero, while a component of the vector is not zero.
False
An object can be in motion and still have zero net force acting on it.
True
In order to move a massive crate sitting on the floor, the force you apply to the crate has to overcome the force of the crate pushing back on you.
False
An object can be moving in one direction while the net force acting on it is in another direction.
True
An object at rest has no forces acting on it.
False
A bird cage, with a parrot inside, hangs from a scale. The parrot decides to hop from one perch to another (without flapping its wings). The total weight of the parrot and cage is 50 N. For the following questions, assume that the scale responds rapidly enough that it gives an accurate reading at every instant.
What is the reading on the scale before the parrot jumps?
50 N
A bird cage, with a parrot inside, hangs from a scale. The parrot decides to hop from one perch to another (without flapping its wings). The total weight of the parrot and cage is 50 N. For the following questions, assume that the scale responds rapidly enough that it gives an accurate reading at every instant.
What is the reading on the scale as the parrot starts its jump?
More than 50 N.
A bird cage, with a parrot inside, hangs from a scale. The parrot decides to hop from one perch to another (without flapping its wings). The total weight of the parrot and cage is 50 N. For the following questions, assume that the scale responds rapidly enough that it gives an accurate reading at every instant.
What is the reading on the scale when the parrot is in the air?
Less than 50 N.
A bird cage, with a parrot inside, hangs from a scale. The parrot decides to hop from one perch to another (without flapping its wings). The total weight of the parrot and cage is 50 N. For the following questions, assume that the scale responds rapidly enough that it gives an accurate reading at every instant.
What is the reading on the scale as the parrot lands on the other perch?
More than 50 N.
Stones are thrown horizontally, with the same initial velocity, from the tops of two different buildings, A and B. The stone from building A lands 4 times as far from the base of the building as does the stone from building B. What is the ratio of building A’s height to building B’s height?
16
The potential energy of a system can be negative.
True
If the force on an object is zero, the potential energy of the system is zero.
False
If the potential energy of the system is zero, the force on the object is zero.
False
You drop a ball to the ground from rest, and, from the same height, throw a second identical ball down to the ground. Their change in gravitational potential energies are different.
False
When air resistance is taken into account, a ball thrown directly upward spends more time on the way down than on the way up.
True
A slow-moving elephant can have more kinetic energy than a fast-moving cheetah.
True
Friction can do positive work on an object.
True
Static friction does no work on an object.
False
Motor A does twice the work as motor B. Therefore, motor A produces twice as much power as motor B.
False
A massive elephant can have less kinetic energy than a lightweight gazelle.
True
Only the net force acting on an object can do work.
False
