Wireless Pulley Sensor Redy

Quick Answer: The Redy wireless pulley sensor is a pulley wheel whose rotation is sensed and converted into the distance a string moves over it, with distance, velocity and acceleration logged wirelessly. A wireless pulley sensor is used in mechanics practicals such as Newton’s second law and the Atwood machine.

Motion Measured at the Wheel

A pulley sensor tracks the rotation of its wheel, often with spokes interrupting a light beam or with a rotary encoder. Knowing the wheel’s circumference, the software converts rotation into the length of string that has passed over it. Because the string is tied to a trolley or a hanging mass, that is also how far the object has moved.

The classic use is Newton’s second law: a trolley on a level track is pulled by a string that runs over the pulley to a falling mass. Changing the hanging mass changes the accelerating force, and the logged velocity graph gives the acceleration directly. An Atwood machine, with two masses hung over the pulley, shows how a small difference in mass produces a slow, easily measured acceleration.

Compared with the ultrasonic wireless motion sensor, the pulley sensor needs no clear line of sight and ignores stray objects, but it only measures motion carried along the string. The clamp type, wheel size and bearing friction are not stated in the title.

Applications

• Newton’s second law with a trolley pulled by a hanging mass
• Atwood machine experiments with two unequal masses
• Finding the acceleration due to gravity from a falling mass
• Energy transfer as gravitational potential energy becomes kinetic energy

Specifications

Care & Handling

• Use light, strong thread that sits in the groove without slipping.
• Clamp the pulley firmly to the bench edge, square to the line of the string.
• Keep the bearing clean and free of dust, since friction affects the results.
• Catch falling masses in a box of soft material so the string and pulley are not jerked.

Why Choose LabEquip

Physics teachers covering forces and energy with data-logging buy pulley sensors because they make Newton’s second law quick to repeat. LabEquip has it in its chemistry lab equipment range; clamp and wheel questions can be sent through the contact page.

Frequently Asked Questions

How does a pulley sensor measure distance?

It counts how far the wheel turns, often using spokes that interrupt a light beam or an encoder. Multiplying the number of turns by the wheel’s circumference gives the length of string that has passed over it.

How do I test Newton’s second law with the pulley sensor?

Pull a trolley along a level track with a string running over the pulley to a hanging mass. Record acceleration for several hanging masses, keeping the total mass constant by moving masses from the trolley to the hanger.

Why is the measured acceleration lower than expected?

Friction in the track and pulley bearing, the mass of the string and the inertia of the pulley wheel all reduce acceleration. Tilt the track slightly to offset friction and use light thread.

What is an Atwood machine?

Two masses hang on either side of a pulley on one string. When they are slightly unequal, the system accelerates slowly, which makes the motion easy to measure and to relate to the difference in weight.

Can the string slip on the pulley?

Yes, if it is too thick, too smooth or too slack. Slipping makes the recorded distance less than the true movement, so use thin thread that seats well in the groove.

Is the pulley sensor better than a motion sensor?

It is more reliable for motion along a string and is unaffected by stray echoes. A motion sensor is more flexible for objects that move freely, such as falling balls or walking students.

Last Updated: September 2026