Topic - Physics for my Child - 15 SENTENCES REQUIRED - TYPED ONLY Instructions:

Question

Topic - Physics for my Child - 15 SENTENCES REQUIRED - TYPED ONLY

Instructions: (For this assignment write THREE PARAGRAPHS, with Each written at a college level and with at least five sentences, including a topic sentence and three or more specific, accurate detailed supporting sentences, and a conclusion sentence.)

Describe the three topics in one paragraph each to your 5th Grader who has no familiarity with physics. You must NOT use physics terms without defining them at a level of explanation a 10 YEAR-OLD will understand.

1) Energy & Oscillations, referring to the study of the operations of work and energy as a different method of analyzing how forces cause motion complements Newton's approach. For example, provide definitions and units for work, energy, and power while listing several forms energy can take, describe how work & energy cause motion, or provide examples of oscillatory motion in everyday life.

2) Momentum & Impulse, referring to using the principles to analyze physical phenomena (collisions and other short interactions between objects). For example, recall definitions and units relating to momentum & impulse and explain how force and time are related to momentum change in a collision, or compare and contrast the conservation laws of energy and momentum.

3) Rotational Motion of Solid Objects, referring to their analysis using rules similar to those in translational motion regarding physical objects may rotate in addition to their translational motion. For example, compare and contrast rotational kinetic energy versus linear kinetic energy, compare and contrast angular momentum versus linear momentum, or explain how torque affects motion.

Explanation / Answer

1) Energy and Oscillation:

Energy is nothing but it’s a property which is transferred to an object in order to perform work. It can be converted into one form to another, but not created or destroyed. The SI unit of energy is joule, which is also defined as “the work of moving an object through a distance of 1 m by applying a force of 1 N”. This is also a definition of work done. So in short, the work done to move any object is also a measure of energy. Power is defined as rate at which work is done. Or one can say it is the ratio of energy to time.

In the different forms of energy we have the kinetic energy of a moving object, the potential energy stored by an object due to it’s position, the elastic energy stored by stretching of a bow or spring, the chemical energy released due to burning of fuel, the energy of radiation carried by light from the sun, and the thermal energy due to an object's temperature.

For a car traveling at a speed of 40 mph, changes it’s speed to 60 mph. In this cars’ kinetic energy increases as it depends on mass and speed. This is change in kinetic energy of the car represents work done by a person who is driving it.

Oscillatory motion is type of motion in which object gets displaced to and fro around it's mean position. The motion of a pendulum in a clock is an example of oscillatory motion. Even the mass attached at the end of the spring when stretched and released performs oscillatory motion which can be sideways or up and down.

2) Momentum & Impulse:

Momentum is nothing but the product of mass and its velocity. So momentum depends on quantity of matter i.e. mass and how fast it is moving i.e. its velocity. So the unit of momentum which is also known as linear momentum is kg*m/s.

Momentum comes into picture when an object of mass ‘m’ is moving with a velocity ‘v’. If the velocity is increased or decreased then the momentum for the given mass varies. The momentum is denoted by ‘p’ and written in formula as,

P = m*v

Momentum is a vector quantity as we mention a direction for an objects motion i.e. velocity having mass m.

In an application of change in momentum with respect to time we have Newton’s second law of motion. The relationship between the force, time, and change in momentum explains one more important concept known as impulse.

Impulse J is defined as the change in momentum or also defined as the product of the force and the time. i.e. J = F*t

A net force which causes acceleration and a change in the velocity of the body till it acts. A force applied over a longer time produces a bigger change in linear momentum than the same force applied for short time. During the collision of two objects, the impulse will be maximum when they come in contact for very short period. Collision of a heavy duty truck with a car is an example of large impulse.

Based on the concept of collision we have to consider momentum and energy conservation. Most of the cases of collisions are of momentum conservation which is also known as inelastic collision. In these energy is not conserved i.e. it is lost through heat most commonly. The collision in which energy along with momentum is conserved is known as elastic collision. When we say the word conserved, it means initial and final numbers are equal.

3) Rotational motion of solids:

Rotational motion of an object is also referred as the motion around a fixed axis.

In translational motion, object traverses in a straight line, while in rotational motion every particle in the body moves in a circle about a single line.

We know that in translational motion object posses linear velocity on the same line of in rotational motion, object (each particles of solid) posses rotational velocity which is also known as angular velocity.

In translational motion kinetic energy is given by,

K.E. = ½*m*v²

While in rotational motion for a given solid it is given by,

K.E. = ½*m*²*r   (where, = angular velocity of solid around an axis, and r = radius or distance from the axis of rotation.

We consider rotational motion of circular objects like a disc, cylinder or a ring.

For an object performing a translational motion we define linear momentum p = m*v. While for a solid like a cylinder performing a rotational motion we consider angular momentum L as, L = r*p. In simple words it is defined as moment of linear momentum. So, we can write, L = r*(mv) = mvr.

Now for a disc and a rod passing through its center perpendicular to the plane of a disc, if we apply force perpendicular at one end which causes a circular motion. This force acting at one of the disc through a distance of radius r, results in torque which is also known as a couple. It is given by,

= r*F

The torque always exists in pair of forces acting in opposite direction.

Tightening of a screw is an example of a torque playing an important role. It depends on the distance at which the force is applied. More is the distance from the axis of rotation lesser will be the force required.

In our daily life we use the application of torque while closing the door. We need lest effort to close the door if we apply a perpendicular force at the edge of a door.

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