A car is moving forward and its brakes are being applied. Which of the following is true?
A. The car's velocity is forward, and its acceleration is
... [Show More] forward.
B. The car's velocity is backward, and its acceleration is forward.
C. The car's velocity is backward, and its acceleration is backward.
D. The car's velocity is forward, and its acceleration is backward.
D. The car's velocity is forward, and its acceleration is backward.
A car moves forward along a horizontal road in a straight line at constant speed. The net force on the car is _______.
zero
You are pushing a file cabinet across a floor in a straight line at a constant speed. Which of the following can you correctly conclude about the forces acting on the file cabinet?
A, If you were to exert twice as much force on the file cabinet, it would slide across the floor at twice its original speed.
B. The force that you are exerting on the file cabinet is greater than the force that friction is exerting on it.
C. The force that you are exerting on the file cabinet is greater than the force of friction with the cabinet's weight.
D. The force that you are exerting on the file cabinet is equal and opposite to the force that friction is exerting on it.
D. The force that you are exerting on the file cabinet is equal and opposite to the force that friction is exerting on it.
Inertia is an object's _______________________________________.
tendency to remain stationary or continue moving in the same way.
The mass of an object measures _____________________________.
the amount of matter in an object.
Which of the following is used to increase friction?
A. spraying a lubricant onto a squeaky wheel
B. scattering sand on icy roads
C. waxing floors
B. scattering sand on icy roads
The force that slows down a person falling is called __________________.
air resistance
If the distance between two objects increases, the force of gravity between them _________________.
decreases
A car decreases its speed from 40 miles per hour to 20 miles per hour. Its linear momentum _____________________.
is half as much
In physics, work is _______________________________________________________________________________.
the energy transferred from one object to another via a force acting through a distance.
Which of the following statements is correct?
A. Potential energy is the energy of speed and kinetic energy is the energy stored in an object.
B. Potential energy is the energy of mass and kinetic energy is the energy of gravity.
C. Kinetic energy is the energy an object as a result of its motion, and potential energy is the energy of position or deformation.
C. Kinetic energy is the energy of an object as a result of its motion, and potential energy is the energy of position or deformation.
A truck increases its speed. What happens to its kinetic energy?
A. not enough information
B. it decreases
C. it increases
C. it increases
In which of the following situations is the object's potential energy changing?
A. a child sledding down a hill
B. a jug of milk standing on the top shelf in a refrigerator
C. a man biking at 20 miles per hour on a straight road
D. a person rowing a canoe on a lake
A. a child sledding down a hill
The figure below shows a pendulum. Assume that there are no frictional losses. The ball is displaced to point A and released. As the ball moves, it passes, in order through points B, C, D, and E, and then again through points D, C, B, and so on. Answer the following questions.
The ball has the greatest potential energy a point ____.
The ball has the greatest kinetic energy at point _____.
The ball has the greatest total mechanical energy at point ____.
A
C
B
Which has a greater thermal energy, coffee at 80°C in a cup or water at 80°C in a swimming pool?
A. The water in the pool has a greater thermal energy, because it contains many more molecules, and thermal energy measures the average energy of the particles.
B. The coffee and the water in the pool have the same thermal energy, which in both cases is 80°C.
C. The water in the pool has a greater thermal energy, because it contains many more molecules, and thermal energy measures the total energy of all the particles.
C. The water in the pool has a greater thermal energy, because it contains many more molecules, and thermal energy measures the total energy of all the particles.
A train traveling 50 mph slows down and stops once the brakes are applied. The train's kinetic energy ________________________________________.
changes to the thermal energy of the brakes.
When energy changes from one type to another, the total energy __________________.
The above statement is known as _____________________________________.
remains constant
the law of conservation of energy
An unstretched spring is slowly from street level to the top of a tall building. Compared to street level, the spring has more _______________________________________.
Suppose you drop the spring from the top of the building and it toward the street below. Neglecting non conservative forces, such as air resistance, the kinetic energy of the spring at the instant just before it hits the street is ________________________________________.
If air resistance is not neglected in the previous question, the kinetic energy of the spring at the instant just before it hits the street is ________________________________________.
gravitational energy at the top of the building
about equal to its gravitation potential energy at the top of the building
greater than its gravitational potential energy at the top of the building. [Show Less]