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## Convert pound-force-second [lbf·s] to gram-force-hour [gf·h]

1 pound-force-second [lbf·s] = 0.125997238148267 gram-force-hour [gf·h]

#### Logarithmic Units.

From the history, definitions, and classification of logarithmic units to interesting examples of their use in acoustics, telecommunications, photography, and other fields.

More about momentum

Momentum is Mass Times Velocity

Some Momentum Properties

We encounter impulse and momentum in our everyday life. In many situations in the real world, such as sledding or snowboarding, an object must gain speed and momentum as it moves. Sometimes two or more objects collide, for example, billiard balls or a bowling ball with pins. In many sports, people also collide. Examples of collisions in sports activities are hockey checks, American and Canadian football tackles. Players who are good at predicting the resulting path of colliding objects have better chances of helping their teams win the game. And every time such an estimate is made, the law of conservation of momentum is used.

Even more often, momentum is spoken of in studies at the microscopic level, for example, when studying the behavior of gas molecules that absorb energy, come into motion, gain some momentum, begin to collide with each other, and transfer their momentum to other molecules.

When bodies interact for a short period of time, very large forces can act on them. As a result of the action of these forces, the shape of the object at the moment of impact can change. In hockey, the boards deform momentarily when a player collides with them. The more the boards are deformed, the less chance of injury to the player’s head, shoulders, or ribs. Another indication of the presence of these forces is a change in the direction of movement of an object. If a goaltender gloves a shot, you can see how the puck impact affects the movement of the goaltender's hand.

## Momentum is Mass Times Velocity

**Linear momentum** or simply momentum * p* of an object is defined as the product of its mass and velocity. Because in this product, the velocity is a vector, momentum is also a vector quantity and has the same direction as the velocity:

In the SI, momentum is measured in kilogram-meters per second (kg·m/s). This unit is dimensionally equivalent to the impulse unit newton-second (N·s):

When the momenta of two objects are compared, both the mass and the velocity of both objects need to be compared.

The two photographs show the same girl. On the left photo, she is moving down the hill at high speed and her momentum is greater than on the right photo

Compare, for example, the momenta of the same young snowboarder when she goes up and moves down the hill. Although this is the same girl with the same mass, her momentum is different in the two situations shown in the picture above. When she goes uphill, her momentum is very small. When she quickly descents from the hill, however, her momentum is several times greater because her speed is quite high.

In real life, no moving object has constant momentum because its velocity is rarely constant. It is more accurate to talk about the instantaneous momentum of a body if it is possible to measure its instantaneous mass and velocity.

Let’s consider an example. Let’s try to calculate the instantaneous momentum of this girl moving downhill. This moment is shown in the left picture. Her mass is 35 kg, the mass of the snowboard and helmet is 2 kg. The velocity at the moment shown in the left photo is 4 m/s. The girl moves towards the south. We consider the girl and the snowboard as one system since they move together as one unit. This is also a closed system since it does not lose its mass and no external forces act upon it. The total mass of this system is 35 + 2 = 37 kg. The momentum of the system is directed in the same direction as its velocity. Therefore, the magnitude of the girl’s momentum is

Thus, the momentum of this young snowboarder is 152 kg·m/s and is directed to the south. Let's use our calculator to convert this value to US Traditional Units:

152 kg·m/s = 1098 lb-ft/s

## Some Momentum Properties

**Sum of momenta of several bodies**. The momentum of a mechanical system consisting of several bodies is the vector sum of momenta of all bodies included in the system.

**Momentum conservation**. The momentum of a closed system, which is not affected by any external forces (or they are compensated) and does not exchange any matter with its surroundings, remains constant. This is known as the **law of conservation of momentum**.

**Conservation during collisions**. To determine the motion of objects after a collision, one must know not only their momenta, but also their kinetic energy, which is, unlike momentum, not necessarily conserved. If the kinetic energy of the colliding bodies is conserved, the collision is called elastic and if not, it is called an inelastic collision. In the latter case, kinetic energy is converted into thermal energy.

You will find more information about momentum in our Impulse and Momentum Calculator.

This article was written by Anatoly Zolotkov

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### Mechanics

**Mechanics** is the branch of physics, which studies the behavior of physical bodies when subjected to forces or displacements, and the subsequent effects of the bodies on their environment.

### Momentum

**Linear momentum**, **translational momentum** or simply **momentum** is a vector physical quantity that is a measure of the mechanical movement of a body. It is the product of a body’s mass multiplied by the velocity of the center of mass of the body. Since momentum is the product of a vector (velocity) and a scalar (mass), momentum is a vector quantity with magnitude and direction. Its direction is the same as that of velocity.

In SI, the unit of measurement of momentum is a kilogram-meter per second (kg·m/s), which is equivalent to newton-second.

### Using the Momentum Converter

This online unit converter allows quick and accurate conversion between many units of measure, from one system to another. The Unit Conversion page provides a solution for engineers, translators, and for anyone whose activities require working with quantities measured in different units.

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You can use this online converter to convert between several hundred units (including metric, British and American) in 76 categories, or several thousand pairs including acceleration, area, electrical, energy, force, length, light, mass, mass flow, density, specific volume, power, pressure, stress, temperature, time, torque, velocity, viscosity, volume and capacity, volume flow, and more. **Note:** Integers (numbers without a decimal period or exponent notation) are considered accurate up to 15 digits and the maximum number of digits after the decimal point is 10.

In this calculator, E notation is used to represent numbers that are too small or too large. **E notation** is an alternative format of the scientific notation a · 10^{x}. For example: 1,103,000 = 1.103 · 10^{6} = 1.103E+6. Here E (from exponent) represents “· 10^”, that is “*times ten raised to the power of*”. E-notation is commonly used in calculators and by scientists, mathematicians and engineers.

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