Work can be either positive or negative: if the force has a component in the same direction as the displacement of the object, the force is doing positive work. If the force has a component in the direction opposite to the displacement, the force does negative work.

Rule: if intercept is less than or = 5% of max Y value, the intercept is negligible and you may drop it from the equation; if intercept is greater than 5% of max Y value, it is significant and you must keep it as part of the final equation.

What is Work, Energy and Power?
Work
Definition	Work is said to be done when a force applied to an object moves that object.
Formula	We can calculate work by multiplying the force by the movement of the object. W = F × d
Unit	The SI unit of work is the joule (J)

Mathematically, work can be expressed by the following equation. W = F • d • cos Θ where F is the force, d is the displacement, and the angle (theta) is defined as the angle between the force and the displacement vector.

Zero work is done when the displacement of a body is zero or perpendicular (θ=900,cosθ=0) to the direction of force applied, then work done is zero. Thus, the force applied and the displacement are in perpendicular directions. So, the work done is zero.

1) A simple example of zero work is when you stand holding a bag in your hands and do not move it. Your hands apply a force on the bag to balance the force of gravity exerted on it but since there is no displacement of the bag, the work done on it by you (your force) and also the gravity is zero.

Zero work is defined when force and displacement are perpendicular to one another and when force or displacement is zero. Example: The force acts in a downward direction, When displacement operates in the forward direction. If you push a wall, it doesn’t move there’s no work done.

Gravity is a constant force. Hence, work by gravity is constant for a given displacement. The particle retains the kinetic energy on return to same vertical position. Work by gravity for horizontal displacement is zero as force and displacement are at right angle.

If work is done on the system, its sign is positive. If work is done by the system, its sign is negative.

Negative work is performed if the displacement is opposite to the direction of the Force applied. Example: Work was done the gravity on a rocket going perpendicular upwards.

When there is a force applied to the object it causes the object to move and work is done by the force. If the object is not moved by the applied force then no work is done.

NO WORK IS DONE if the force you exert does not make the object move. Work is done when the force (F) applied to the object causes the object to have a displacement (d) in the same direction as the force applied. 6. A GIRL IS PULLING HER TOY CAR • Yes, the situation is an example of work.

Work is done whenever a force or a component of a force results in a displacement. No component of the force is acting in the direction of motion when the book is moved horizontally with a constant velocity. The force and the displacement are independent. No work is done by the hand on the book.

Explanation: If an object is moving with a constant velocity, then by definition it has zero acceleration. So there is no net force acting on the object. The total work done on the object is thus 0 (that’s not to say that there isn’t work done by individual forces on the object, but the sum is 0 ).

The net force on the object is zero. The force you are exerting is equal in magnitude and opposite in direction to the force of gravity. As you are lifting the object you are doing work on the object.

Acceleration (a) is the change in velocity (Δv) over the change in time (Δt), represented by the equation a = Δv/Δt. This allows you to measure how fast velocity changes in meters per second squared (m/s^2). Acceleration is also a vector quantity, so it includes both magnitude and direction.

No work is done in either case. Work done on a body is equal to the increase in the energy of the body, for work transfers energy to the body. If, however, the applied force is opposite to the motion of the object, the work is considered to be negative, implying that energy is taken from the object.

Work is the energy needed to apply a force to move an object a particular distance, where force is parallel to the displacement. Power is the rate at which that work is done.

This means that zero work is being done as the force and distance are not applied in the same direction. Richard G. Examples: Pushing a car horizontally from rest; shooting a bullet (the powder does the work); walking up stairs; sawing a log.

This energy comes from the chemical energy in your body and most of them are converted into heat and lost to the surrounding. In this situation, no energy is transferred to the book, so no work is done. You can feel the different energy consumption when your arm is stretched in different angle.

As you hold the weight, you exert a force on it, but there is no displacement, since the bag does not move, so the work is zero. That does not mean that you do not lose energy – exerting force by skeletal muscles requires that they spend energy, and you will get tired.

The total amount of work done on a body equals the change in its kinetic energy. Work done is said to be positive when an external force acts in the direction of motion of the body. If positive work is done on a body by an external force, then the body gains kinetic energy.

Force is the transfer of energy. It doesn’t require energy, it’s what we perceive as energy moves from one thing to the other.

The 5% rule is a way of determining if the y-intercept is significant to the equation or negligible due to calculation errors. Negligible means it is insignificant or you can neglect it because it is of a small enough value. In order to determine how small is small enough to call it zero, we use the 5% rule.

CGS Unit of Power Power is defined as the rate of doing work given by, Power = Work / time. The CGS unit of power is erg per second.

Definitions and conversion factors of CGS units in mechanics

Quantity	Quantity symbol	CGS unit name
length, position	L, x	centimetre
mass	m	gram
time	t	second
velocity	v	centimetre per second

The cgs Gaussian system is nonetheless commonly used in theoretical physics, while the MKS system (based on the meter, kilogram, and second) is commonly used in engineering and physics instruction.

The most commonly used unit for dynamic viscosity is the CGS unit centipoise (cP), which is equivalent to 0.01 Poise (P).

1.4. The basic units of the cgs system are cm (centimeter), g (gram), and s (second). But, the fourth unit depends on whether it is based on the cgs electrostatic system of units (esu) or based on the cgs electromagnetic system of units (emu).

MKS is the system of units based on measuring lengths in meters, mass in kilograms, and time in seconds. MKS is generally used in engineering and beginning physics, where the so-called cgs system (based on the centimeter, gram, and second) is commonly used in theoretic physics.

The MKS system of units is a physical system of measurement that uses the meter, kilogram, and second (MKS) as base units.

1g=10−3kg. Substitute the values of dyne, cm and g in equation (i). This further implies that, G=6.67×10−11m3kg−1s−2. Hence, the value of the gravitational constant in MKS system is G=6.67×10−11m3kg−1s−2.

In order to convert the MKS system to the CGS system, the conversion is done as follows: For Length: Since, 1 metre = 100 centimetre Therefore, multiply the given length value by 100. For Weight: Since, 1 kilogram = 1000 gram Therefore, multiply the given weight value by 1000.

The MKS units use meters 1 m , kilograms 1 kg and seconds 1 s , and the CGS units use centimeters 1 cm = 0.01 m , grams 1 g = 0.001 kg and seconds 1 s ….CGS units in mechanics.

Quantity (symbol)	CGS unit name (symbol)	Equivalent in SI units
acceleration (a)	gal (Gal)	10⁻² m/s²
force (F)	dyne (dyn)	10⁻⁵ N

6.67x