1.
Friction is a .......... force.
Correct Answer
A. Conservative
Explanation
Friction is a contact force that opposes the relative motion or tendency of motion between two surfaces in contact. It arises due to microscopic irregularities on surfaces, impeding smooth motion. This force is crucial in various practical applications and influences the dynamics of objects in contact.
2.
Which direction does Friction act with respect to motion?
Correct Answer
B. Opposite direction
Explanation
Friction is a force that opposes the motion of an object. When an object moves, the direction of friction is opposite to the direction of its motion. This means that friction acts in the opposite direction to the applied force or the direction in which the object is trying to move. Therefore, the correct answer is "opposite".
3.
If an object experiences a frictional force the object loses ..........
Correct Answer
kinetic energy
Explanation
When an object experiences a frictional force, it loses kinetic energy. This is because friction acts in the opposite direction to the object's motion, causing it to slow down and eventually come to a stop. As the object loses speed, its kinetic energy decreases. Friction converts the object's kinetic energy into other forms, such as heat or sound energy. Therefore, the correct answer is kinetic energy.
4.
The displacement of the block is parallel to the surface of the ramp, therefore the frictional force is also parallel to the ramp but in the same direction of the displacement.
Correct Answer
B. False
Explanation
The displacement of the block being parallel to the surface of the ramp does not necessarily mean that the frictional force is also parallel to the ramp. The direction of the frictional force depends on the angle of the ramp and the force applied to the block. It can be either parallel or perpendicular to the ramp, depending on the specific conditions. Therefore, the statement is false.
5.
There is friction when two objects are not in contact.
Correct Answer
B. False
Explanation
Friction is a force that opposes the relative motion or tendency of motion between two surfaces in contact. It only occurs when two objects are in contact, not when they are not in contact. Therefore, the statement that there is friction when two objects are not in contact is incorrect.
6.
Static friction is always larger than dynamic friction.
Correct Answer
A. True
Explanation
Static friction is the force that prevents an object from moving when a force is applied to it. Dynamic friction, on the other hand, is the force that opposes the motion of an object that is already in motion. Static friction is always larger than dynamic friction because it takes more force to overcome the initial resistance and start the motion of an object than it does to keep it in motion. Once an object is moving, the force required to keep it moving is typically less than the force required to start its motion.
7.
Static friction and dynamic friction have the same magnitudes.
Correct Answer
B. False
Explanation
Static friction and dynamic friction are two different types of friction. Static friction is the force that prevents two surfaces from sliding past each other when they are at rest, while dynamic friction is the force that opposes the motion of two surfaces sliding past each other. The magnitudes of static friction and dynamic friction are not the same. Static friction is generally greater than dynamic friction, which means it requires more force to overcome static friction and initiate motion than to keep an object in motion. Therefore, the correct answer is False.
8.
The energy that is lost can completely flow back into the object.
Correct Answer
B. No
Explanation
The statement is typically false. In many physical systems, the energy that is lost, especially through processes like friction or heat dissipation, is often dissipated in a way that makes it challenging or impossible for it to completely flow back into the object. This is due to the principles of thermodynamics, which dictate the directionality of energy flow in closed systems.
9.
Friction is most often experienced when
Correct Answer
A. When two objects are in contact
Explanation
Friction is a force that opposes the relative motion or tendency of motion between two surfaces in contact. It occurs when there is contact between two objects, and the surfaces of these objects interact with each other. Friction is caused by the irregularities and roughness present on the surfaces, which interlock and resist the motion. Therefore, the correct answer is when two objects are in contact.
10.
Kinetic energy can be found in
Correct Answer
C. Both
Explanation
The correct answer is both. Kinetic energy refers to the energy possessed by an object due to its motion. Heat energy can be considered a form of kinetic energy as it is the result of the movement of particles within a substance. Similarly, sound energy is also a type of kinetic energy as it is produced by the vibration of particles in a medium. Therefore, both heat and sound can be categorized as forms of kinetic energy.
11.
Friction can be explained as:
Correct Answer
A. A force that always opposes motion between two surfaces.
Explanation
Friction is a force that resists the relative motion or tendency of such motion of two surfaces in contact. It acts opposite to the direction of motion or the potential motion and is generally dependent on the nature of the surfaces in contact. Friction can impede the motion of objects and is a crucial factor in understanding the behavior of objects in contact with each other.
12.
Dynamic friction is
Correct Answer
A. Kinetic
Explanation
Dynamic friction refers to the resistance encountered when two surfaces are in relative motion. It is also known as kinetic friction. This type of friction occurs when an object is sliding or moving across another surface. It is different from static friction, which is the resistance experienced when an object is at rest and trying to be moved. Therefore, the correct answer is kinetic.
13.
When an objects starts to move, friction is
Correct Answer
B. Decreased
Explanation
When an object starts to move, the friction between the object and the surface it is on decreases. This is because static friction, which is the force that opposes motion between two surfaces in contact, is generally greater than kinetic friction, which is the force that opposes the relative motion of two surfaces sliding past each other. As the object overcomes the initial static friction and starts moving, the friction between the surfaces decreases, allowing the object to move more easily.
14.
If you push on a heavy object with a small force it will not slide. Friction will prevent it from sliding.
Correct Answer
A. True
Explanation
When you push on a heavy object with a small force, the force of friction between the object and the surface it is on will be greater than the applied force. Friction is a force that opposes motion, so it will prevent the object from sliding. Therefore, the statement is true.
15.
Friction is caused by
Correct Answer
A. Irregularities in an object
Explanation
Friction is caused by irregularities in an object. These irregularities refer to the microscopic bumps and imperfections present on the surface of objects. When two objects come into contact, these irregularities interlock, creating resistance to motion. The rougher the surface, the greater the frictional force. This phenomenon explains why it is harder to slide a rough object on another rough surface compared to a smooth one. Therefore, irregularities in an object play a crucial role in generating friction.
16.
Static energy is
Correct Answer
B. two solid objects that are not moving relative to each other
Explanation
Static energy refers to the potential energy stored in an object or system due to its position or configuration. In this context, two solid objects that are not moving relative to each other would have static energy because there is no kinetic energy associated with their motion. The absence of relative motion allows for the potential energy to be stored in the system.
17.
Objects lose which of the following as they fall?
Correct Answer
A. Potential energy
Explanation
Potential energy refers to the energy stored in an object due to its position or configuration. When an object is raised to a certain height, it possesses gravitational potential energy relative to the ground. This is the energy it could potentially convert into other forms, such as kinetic energy, if it were to fall. As objects fall, they lose this stored potential energy. The force of gravity pulls the objects down, converting their potential energy into kinetic energy, which is the energy associated with motion. This process continues until the object hits the ground or another surface, at which point its potential energy has been fully converted into kinetic energy. Therefore, the correct answer is that objects lose potential energy as they fall. While they also lose height and may eventually lose acceleration due to air resistance, the main energy transformation during free fall is the conversion of potential energy to kinetic energy.
18.
Gravity is a
Correct Answer
B. Non-conservative Force
Explanation
While gravity can exhibit some characteristics of a conservative force in certain contexts, it is generally considered non-conservative due to the presence of non-conservative forces, such as frictional forces or other dissipative forces, which can result in energy loss. In an ideal, isolated system with only gravitational forces acting, gravity would be considered a conservative force, as energy can be transferred between potential and kinetic forms without loss. However, in real-world systems, friction and other non-conservative forces are often present, which results in energy loss and makes gravity a non-conservative force. For example, when an object falls to the ground, some of the gravitational potential energy is converted to heat due to frictional forces, rather than being completely converted to kinetic energy. This energy loss makes gravity a non-conservative force. Therefore, gravity is a non-conservative force, which means it does not satisfy the principle of conservation of energy in the presence of dissipative forces.