PHYSICS OF PLACING A DOOR HANDLE

Kick a ball on the ground. It goes in a straight line. OK. Here you are applying a force straight on the ball. Suppose, you turn a car driving wheel, what exactly you are doing? You hold the wheel at the edge and apply a force perpendicular to the axis of rotation.
We will take another example to understand more clearly. The opening and closing of a door is also a rotation. Here, you push the door horizontally at the edge. That is, you are applying the force perpendicular to the axis of rotation and at a distance from the hinges(axis of rotation).
This kind of rotating or turning force is called torque. It is the product of the force applied and the distance from the axis (Torque = F * r).
From the formula, we can understand, if you either increase force or distance, the torque will also increase.

Suppose, a mechanic wants to loosen a heavy bolt in a machine. He takes a spanner or a wrench and applies a force as explained above to create a 'turning effect'. If he fails, he takes another rod attaches to the instrument and tries again. He mostly succeeds this time because he has doubled the length of spanner and hence doubled the torque. This is an easy way to magnify a turning force.
Coming to our door, if the handle is placed at the edge, it is easy to close and open the door. If the handle is placed at the middle or near the keel, it is going to be difficult, because the torque will decrease.
Consider a Bi-cycle. The shaft connected between the center of gear and the pedal is called crank-shaft. The crankshaft converts the linear motion of the feet into rotatory motion of the gear and also provides the necessary torque. The length of the shaft determines the torque. Crank-shaft also exists in all the vehicle engines.
Turning effect is based on a lever action. "Give me a place to stand," Archimedes is said to have promised, "and I will move the world."
The above statement clearly illustrates that a length can multiply a turning force many times.
-------------------------------------------------------------

Comments

LISSAJOUS FIGURES

Definition: "When a particle is subjected to two sine wave motion or two oscillatory motion at right angles, the particle describes lissajous figures". We know sine wave motion and circular motion is basically same. Hence we draw two circles A and B perpendicular to each other. The circle B rotates twice faster than circle A. That is, frequency of circle B is two times than that of A. A particle at the intersection of two circles is subjected to two sine wave motion A and B at 90 degree simultaneously. The particle will describe figures depending on the frequency and phase of A and B . In our case, the ratio of frequency is 1:2 and the two waves are in phase. To draw lissajous figures : A moving point in both the circles are chosen. Here we should remember; during the time taken by the circle A to complete one rotation, circle B completes two. Hence the points are marked on the circles according to their speed. Then straight lines

THE PARABOLA

A jet of water shooting from a hose pipe will follow a parabolic path. What is the so special about parabola. Y= x^2 Draw a graph for the above equation. It will result in a parabola. This parabola is also called unit parabola. Any equation involving square will yield a parabola. Example: Y = 2x^2 +3x+3 (also called quadratic equation) X= 2 and -2, both satisfies the equation 4 = X^2. Parabolic equations always have two solutions. Any motion taking place freely under gravity follows parabolic path. Examples: An object dropped from a moving train, A bomb dropped from flying plane, A ball kicked upwards. If a beam of light rays fall on the parabolic shaped mirror, they will be reflected and brought to focus on a point. This fact is made use of in Dish Antenna, Telescope mirrors, etc. Inverted parabola shape is used in the construction of buildings and bridges. Because the shape is able to bear more weight. A plane

CASINO'S GAME

Let us find out how the casino survives with mathematics. Say, your friend invite you for a game of dice. You must bet (wager) 2 dollars. If you roll 'six' you will get back 8 dollars. The game will go on for 30 rounds. All sounds good. The probability of rolling 'six' is 1/6. Since the game will be played for 30 times, the 'expected win' is 30*1/6 = 5. That is, you are expected to win 5 rounds out of 30. Hence your gain will be 5 * 8 =40 dollars. ok. This also implies that you will loose 25 rounds. Hence your loss will be 25*2 =50 dollars. Your net gain will be gain-less = 40-50 = -10 dollars. For 30 rounds, the loss is -10 dollars, Hence, for one round =-10/30 = -1/3 dollars. There will be a loss of -1/3 or 0.33 dollars per round. It is not a fair game. Let us make a simple formula to calculate 'Pay out per round\. The probability for a win = p The pay-out in case of win = V No. of rounds = n The expect

sciencecapsules

Search This Blog