1.
Which of the following statements best describes how a pulley works?
Correct Answer
A. A pulley decreases the amount of force needed to lift an object by changing the direction of the force applied.
Explanation
A pulley changes the direction of the force applied, allowing you to pull down to lift an object up, which makes the task easier. Some pulley systems (such as a block and tackle) can also reduce the amount of force needed by distributing the weight of the object across multiple ropes. Pulleys do not reduce weight, friction, or increase speed directly.
2.
This car is an example of friction because there is an interaction between the wheels and the dirt. Friction is a force that occurs in
Correct Answer
B. Contact
Explanation
Friction is a force that occurs when two objects are in contact with each other and there is a resistance to motion. In this case, the car's wheels are in contact with the dirt, and there is an interaction between them that causes friction. Therefore, the car is an example of contact friction.
3.
A machine is
Correct Answer
D. An instrument or device that allows us to do tasks with less effort.
Explanation
The correct answer is "an instrument or device that allows us to do tasks with less effort." This answer is supported by the fact that a machine is typically designed to make tasks easier and more efficient. Machines are created to reduce the amount of physical or mental effort required to perform a task, ultimately making our lives easier.
4.
Which of the following types of levers has the fulcrum positioned between the effort and the load?
Correct Answer
A. First-class lever
Explanation
In a first-class lever, the fulcrum is located between the effort and the load. Examples include seesaws and crowbars. In second-class levers, like wheelbarrows, the load is between the effort and the fulcrum. In third-class levers, such as tweezers or a fishing rod, the effort is applied between the load and the fulcrum.
5.
Which of the following simple machines allows you to lift a heavy object with less force by increasing the distance over which the force is applied?
Correct Answer
C. Inclined plane
Explanation
An inclined plane allows you to lift a heavy object by applying a smaller force over a longer distance. This reduces the effort needed to lift the object vertically. A lever also reduces force but works differently, using a fulcrum to gain mechanical advantage. A pulley system reduces force by redirecting it, and a screw converts rotational force to linear force. Among these, the inclined plane specifically works by increasing the distance over which the force is applied, thus reducing the effort needed to lift the object.
6.
This is a
Correct Answer
B. Compound machine
Explanation
A compound machine is a combination of two or more simple machines working together to perform a specific task. Since the question states "This is a simple machine," it implies that the given object is not just a single simple machine but a combination of multiple simple machines. Therefore, the correct answer is compound machine.
7.
This is an example of a
Correct Answer
A. Simple machine.
Explanation
The question is asking for the classification of the given example. The term "simple machine" refers to a basic mechanical device that helps to perform work, such as a lever or pulley. Since the example does not mention any complexity or combination of multiple machines, it can be classified as a simple machine.
8.
This is a gear and it is an example of an
Correct Answer
C. Element of a machine.
Explanation
The given object is identified as a gear, which is a fundamental component of a machine. Gears are used to transmit motion and power between different parts of a machine, allowing it to perform its intended function. Therefore, the gear can be categorized as an element of a machine.
9.
In this pulley if I apply a force in P down the pulley changes the direction of W and it goes
Correct Answer
up
Explanation
When a force is applied in the downward direction at point P on the pulley, it causes a change in the direction of the weight (W) attached to the pulley. As a result, the weight moves in the upward direction.
10.
The force of the airplane is acting _________________ and this moves the airplane _______________.
Correct Answer
D. Backward -- forward
Explanation
The force of the airplane is acting backward, which causes the airplane to move forward.