CBSE Class 6 Science Machines Worksheet

1. Scissors

Question a) List two types of simple machines used in scissors:
1. Wedge (the two blades act as moving inclined planes or wedges to cut materials)
2. Lever (First-class lever, where the fulcrum is in the middle between the effort and the load)
Answer: 1. Wedge
2. Lever
In simple words: Scissors use sharp blades to cut (wedge) and handles that pivot around a central screw (lever).

Exam Tip: Remember that most cutting tools combine a lever system with wedge-shaped blades.

Question b) Label the fulcrum, the point of effort application, and one possible point of load application on the drawing to the right.
Answer: Fulcrum: The central screw/pivot pin where the two blades cross.
Point of effort application: The inner edges of the finger loops where fingers apply force.
Point of load application: The cutting edges of the blades where the material being cut is placed.
In simple words: The pivot is the fulcrum, your fingers apply effort on the handles, and the object being cut experiences the load at the blades.

Exam Tip: In a first-class lever, the fulcrum is always located between the effort and the load.

2. Adjustable wrench

Question a) List two types of simple machines used in an adjustable wrench:
1. Screw (the adjusting worm gear or thumb screw)
2. Lever (the handle acts as a lever to apply torque to a bolt or nut)
Answer: 1. Screw
2. Lever
In simple words: An adjustable wrench uses a screw mechanism to adjust its jaw width and a long handle as a lever to turn nuts easily.

Exam Tip: The thread mechanism that adjusts the movable jaw is a classic example of a screw machine.

Question Mechanical advantage:
Answer: The mechanical advantage of an adjustable wrench is greater than 1 because the length of the handle (effort arm) is much greater than the distance from the pivot to the load (resistance arm), allowing a small applied force to exert a large turning force (torque) on the nut.
In simple words: A long handle multiplies your force, making it easier to tighten or loosen tight nuts.

Exam Tip: Mechanical advantage in tools with handles is generally the ratio of the effort arm length to the load arm length.

3. Can opener

Question a) List three types of simple machines used in the can opener:
1. Wedge (the sharp cutting wheel that punctures and slices through the metal lid)
2. Wheel and Axle (the turning knob and gear mechanism used to rotate the cutting wheel or advance the can)
3. Lever (the handles used to squeeze the cutting blade into the can and provide mechanical advantage)
Answer: 1. Wedge
2. Wheel and axle
3. Lever
In simple words: A manual can opener combines a sharp cutting wedge, rotating wheels, and squeezing handles.

Exam Tip: Complex household tools almost always use a combination of multiple simple machines.

4. Corkscrew

Question a) List three types of simple machines found on a corkscrew:
1. Screw (the helical metal worm that twists into the cork)
2. Lever (the side arms or handle used to pull the cork out with mechanical advantage)
3. Inclined plane (the spiral thread of the screw is an inclined plane wrapped around a cylinder)
Answer: 1. Screw
2. Lever
3. Inclined plane
In simple words: A corkscrew uses a spiral screw to grip the cork and levers to pull it out smoothly.

Exam Tip: A screw is fundamentally an inclined plane wound around a central shaft.

Question b) What is the pitch of the screw?
Answer: The pitch of a screw is the linear distance between consecutive threads (or the distance the screw advances along its axis in one complete 360-degree rotation).
In simple words: Pitch is the distance between two neighboring ridges on the spiral screw.

Question a) What is the purpose of a single pulley?
Answer: The purpose of a single fixed pulley is to change the direction of the applied force, making it easier to lift or pull loads by pulling downward instead of upward. A single movable pulley helps in multiplying force.
In simple words: A single pulley changes the direction in which you pull a rope or cable.

Exam Tip: A fixed pulley has a mechanical advantage of 1, whereas a movable pulley has a mechanical advantage of 2.

Question b) How many pulleys are there on the skate at your station?
Answer: Standard inline roller skates do not use pulleys; instead, they use multiple wheel-and-axle assemblies (rollers/wheels). If referring strictly to internal pulley-based lacing systems (if present on specific specialized models), the count is typically 0 to 2, but standard recreational roller blades have 0 traditional rope-and-pulley machines (the wheels act as wheels and axles).
In simple words: Roller blades use wheels and axles rather than traditional pulleys with ropes.

Question c) Name another type of simple machine on the skate.
Answer: Wheel and axle (represented by the skate wheels and their rotating axles) or Screw (used in the bolts and fasteners holding the wheels and frames to the boot).
In simple words: The wheels rolling on axles are a classic example of a wheel and axle simple machine.

Exam Tip: Wheels on vehicles, roller skates, and bicycles are all wheel and axle systems designed to reduce friction.