1.
A puck slides along an icy surface. What makes it slow down?
Correct Answer
B. It rubs against the ice
Explanation
As the puck slides along the icy surface, it experiences friction with the ice. Friction is a force that opposes the motion of objects in contact, and in this case, it acts in the opposite direction to the puck's motion. This frictional force between the puck and the ice causes it to slow down over time. Therefore, the correct answer is that the puck slows down because it rubs against the ice.
2.
A boy sits halfway down a grassy slope. What force stops him sliding down?
Correct Answer
C. Friction
Explanation
Friction is the force that stops the boy from sliding down the grassy slope. Friction is the resistance between two objects that are in contact with each other. In this case, the friction between the boy's body and the grassy slope prevents him from sliding further down. As long as the force of friction is greater than the force pulling him down the slope (such as gravity), the boy will remain in place.
3.
On which surface will a toy sledge travel the furthest?
Correct Answer
C. Ice
Explanation
The toy sledge will travel the furthest on ice because ice has a very low friction coefficient. This means that there is less resistance between the sledge and the surface, allowing it to slide easily and cover a greater distance compared to carpet or polished wood, which have higher friction coefficients.
4.
On which surface will a toy sledge travel the least distance?
Correct Answer
A. Carpet
Explanation
A toy sledge will travel the least distance on a carpet surface because the carpet provides more friction compared to polished wood or ice. Friction is the force that opposes the motion of an object, and the rough texture of the carpet increases the friction between the sledge and the surface, causing it to slow down and travel a shorter distance. Polished wood has less friction than carpet, and ice has even less friction, allowing the sledge to slide more easily and cover a greater distance.
5.
The rougher the surface, ...
Correct Answer
A. The greater the friction
Explanation
The rougher the surface, the greater the friction. This is because rough surfaces have more irregularities and bumps, which create more points of contact between the two surfaces. These points of contact increase the resistance to motion, resulting in a higher level of friction.
6.
Which of the following is an example of trying to increase friction?
Correct Answer
B. Spreading grit on icy roads
Explanation
Spreading grit on icy roads is an example of trying to increase friction. Grit, such as sand or salt, is spread on icy roads to provide more traction for vehicles. The rough texture of the grit increases the friction between the tires and the road surface, helping to prevent vehicles from slipping and sliding on the ice. This increases the grip and stability of the vehicles, making it safer to drive on icy roads.
7.
Which of the following statements is true?
Correct Answer
C. Friction is a force that only occurs when surfaces touch each other
Explanation
Friction is a force that only occurs when surfaces touch each other. This statement accurately describes the nature of friction. Friction is the force that opposes the motion of an object when it is in contact with another object or surface. It occurs when there is relative motion or an attempt of motion between the surfaces in contact. Friction can occur between solids, liquids, and gases, as long as there is contact between the surfaces.
8.
Which of the following statements is false?
Correct Answer
B. Friction is never useful
Explanation
Friction is the force that opposes the motion of objects in contact with each other. While it is true that friction can slow things down and stop them from moving, it is not true that friction is never useful. In fact, friction is essential in many everyday activities and technologies. It allows us to walk, drive vehicles, and hold objects without them slipping out of our hands. Friction is also necessary for the operation of brakes, tires, and many other mechanical systems. Therefore, the statement "Friction is never useful" is false.
9.
Air resistance and water resistance are both types of friction. Is this true or false?
Correct Answer
A. True
Explanation
Air resistance and water resistance are both types of friction. This statement is true because both air resistance and water resistance are forces that act in the opposite direction to the motion of an object moving through air or water. These forces are caused by the friction between the object and the medium it is moving through, which slows down the object's motion. Therefore, air resistance and water resistance can be categorized as types of friction.
10.
If you poured oil onto a wooden surface, the friction would ...
Correct Answer
A. Be reduced
Explanation
When oil is poured onto a wooden surface, it acts as a lubricant, reducing the friction between the two surfaces. This is because oil creates a thin layer between the wood and any other object, allowing them to slide more easily against each other. As a result, the friction between the wooden surface and the object is reduced, making it easier for the object to move across the surface.