How Does Torque Work: Every Facts You Need to Know


The torque is a momentum given to the object to set it in the angular motion rotating at its axis of rotation. But how does torque work? Let us talk about the same.

Torque is a force that rotates the object about its axis accelerating the object and is depends upon the applied force. The torque is calculated by finding the force applied and the displacement of the object caused due to imposing force.

How torque is produced?

The torque is produced when the force is applied to the edge of the object such that the object will rotate on the effect of the applied force at a fixed axis of rotation.

The equivalent force in response to applied force is produced in the opposite direction and is equal in magnitude which is responsible for the rotations of the object and hence the object is translational motion.

There are two types of torque depending upon whether the object accelerates on giving the torque or not. The static torque is when there is no acceleration of the object and it moves at a constant speed, whereas the dynamic torque is seen when there is an acceleration of the object.

Suppose you give a torque on gear, and the gear will start rotating with the angular velocity.

how does torque work
The torque on a gear

The amount of force applied to give a torque will be produced at exactly the opposite point on the gear in the opposite direction to set the gear in rotational motion. The speed of the rotating gear is calculated by measuring the angular displacement of the gear per second.

Factors Affecting Torque

The torque depends upon the force applied to displace the object and set it into the rotational motion. The main factor affecting the torque is the moment of inertia of the body, the force applied, distance from the axis of rotation from the point of force applied on the body, and displacement of the object.

The torque is calculated using the formula

τ=Force*displacement

Hence the SI unit of torque is N.m

Since F=ma

τ=ma* displacement

Therefore, the dimension of torque we can write as ML2T-2

The torque on the body follows Newton’s Second Law of Motion, the body is set in the rotational motion on the application of the tangential force which is called a torque.

τ=Iɑ

Where I is the moment of inertia and

ɑ is the angular acceleration

The acceleration of a spinning object is measured in terms of angular acceleration.

How does torque work in a car?

In the case of the car, the torque is applied to the tires to accelerate and also while taking a turn.

This torque on the tires is given by the movement of the piston in the engine of a car, and while the car is taking its turn applies the torque on the tires by giving a torque to the steering wheel of a car.

Suppose a car driver is taking a torque on a turn then he will give torque to the tires of a car. The same is shown in the below diagram.

Torque in a car

The torque that a driver will give with the help of a steering wheel is τ1 due to which the torque τ3 is exerted on the tires of a car to charge the torque initially acting on the tires. The torque τ2 is directed in a front direction to keep the car accelerating forward.

How does torque work on a drill?

The drilling machines are used to make a hole in an object by the rotational motion of the screw used to drill through.

The torque is applied on a drill to rotate the screw, the more is the speed used while drilling the less torque will be imposed hence the more power is more when you drill with a less speed.

On supplying the electric energy, the motor starts rotating and a shaft attached to it rotates the screw.

The rotating screw due to torque

The rotating shaft exerts the torque on the drilling screw and rotates it either clockwise or anti-clockwise. The direction of the torque is shown in the above figure.

How does torque work in a bike?

The speed of a bike depends upon the torque applied on a rear wheel with the help of a chain.

The tires of the bike exert a torque on them to rotate and convert the distance by moving the bike in linear motion. Depending on how much the torque is applied on a rear wheel the tires of a bike take the speed accordingly and accelerate.

The speed of a bike though depends upon the speed of a motor while giving more torque to the rear wheel will achieve the highest speed the bike can run in less time.

Upon kicking on a bike pedal, the force is applied that moves the chain and due to the frictional force between the chain and a rear wheel, the wheel feels the torque on the wheel and accelerates. The same is depicted in the below figure.

The torque applied on the wheels of a bike

As the wheel starts rotating, the torque is transferred to the gears and the gear starts rotating. This is further exerted on the tires and rotates with the equal force of friction applied on the road while accelerating.

How does torque work in a golf shaft?

The game of golf is actually based on two physics concepts, the moment of inertia and torque.

The softer and longer the shaft the more is torque applied by swinging. The torque is created by swinging the shaft and to control it the moment of inertia plays a role that provides the rotational moment of inertia to the ball to spin in the air and accelerated at a greater distance.

Golf shaft and ball; Image Credit: Pixabay

The golf player will always move her body in a specific way that the moment of inertia of a shaft is controlled and felt equally on the ball. Upon swinging the shaft the torque is created due to the momentum and the air drag which is transferred to the ball and it spins at its rotational axis of the moment of inertia gaining enough energy to sway far away traversing through the air.

Frequently Asked Questions

What is torque on a golf ball if the force of 10KN is applied on the ball and is 318 meters?

The torque on the ball is the torque transferred from the golf shaft hence torque felt on the golf ball is equal to the torque of a golf shaft.

We have,

F =10KN

d =318m

The torque is equal to the force imposed and the displacement of a ball, i.e.

τ=Fd

Inserting the values,

τ =10* 318= 3180N.m

The torque of 3180 N.m is applied on a ball to displace it to a distance of 318m with a force of 10KN.

What is the torque exerted on the tire of a car if the angular acceleration of a tire is 4π rad/s2 and the mass of the tire is 28kg and the radius is 25cms?

Given: m =28kg

ω =4π rad/s2

r = 25cm =0.25m

The moment of inertia of tire is

Hence, the torque exerted on the tire of a car is

Hence the torque on the tire is 11 N.m.

How does the object accelerate on application of torque on its body?

The object accelerates due to the equal amount of force is felt on the object in the opposite direction that sets it into motion.

The object moves in the rotational motion as it spins on its axis of inertia, the point where the center of gravity of the object persists. If the rotating object comes in contact it the surface then the object will start moving in a linear motion too along with the rotating motion and the path cover will be equal to the perimeter of the object.

How does torque create a tensional force?

The tensional force is created in the objects like rope or string.

Suppose you apply a torque on the rope by giving it a torque on two ends of the rope in opposite direction, then the tensional force will be generated across the length of the rope.

How does torque deform the object?

The torque is a force applied to the object that set it into motion in angular acceleration.

If the torque is exerted on one end of the object and another point of the object is fixed then the object may be deformed from one of the ends or bend. If the force is applied in the same direction then also the object will bend and even break from the middle of its point.

AKSHITA MAPARI

Hi, I’m Akshita Mapari. I have done M.Sc. in Physics. I have worked on projects like Numerical modeling of winds and waves during cyclone, Physics of toys and mechanized thrill machines in amusement park based on Classical Mechanics. I have pursued a course on Arduino and have accomplished some mini projects on Arduino UNO. I always like to explore new zones in the field of science. I personally believe that learning is more enthusiastic when learnt with creativity. Apart from this, I like to read, travel, strumming on guitar, identifying rocks and strata, photography and playing chess. Connect me on LinkedIn - linkedin.com/in/akshita-mapari-b38a68122

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