Kinematics

The slope of a line drawn tangent to a point on a position vs. time graph represents the instantaneous velocity of the object at that point. It describes how the position of the object is changing at that exact moment in time.

Because it is:

* A property of physical objects

* Something that can be measured (or calculated from other quantities)

Hmm, it is certainly not a physical quantity that is unique to the object! Velocity is relative to some other object. Thus, the can he threw traveled at 12m/s relative to the tree but 220m/s relative to that car.

A position time graph can show you velocity. As time changes, so does position, and the velocity of the object can be determined. For a speed time graph, you can derive acceleration. As time changes, so does velocity, and the acceleration of the object can be determined.
If you are plotting velocity (speed) versus time, the slope is the acceleration.

62 knots is equivalent to approximately 71 miles per hour or 115 kilometers per hour.

4 hours 12 minutes

Depends what you mean by "freely falling". If you consider a body falling toward the earth through a complete vacuum, there is practically no limit to its speed. The gravitational attraction will cause the body to accelerate, so the speed will keep increasing until it collides with the earth.

If the body is falling though the atmosphere, however, we must take air resistance into account.

Let the force (downward) due to gravity be F.

Let the drag coefficient of the falling body be C.

Let m be the mass of the body, and v be the speed of the body.

Then we have the equation;

m dv/dt = F - Cv

The speed will be constant when dv/dt = 0, so then F-Cv=0.

Solving for v we get

v = F/C, which will be the terminal velocity of the falling body.

Close to earth, F=mg. The drag coefficient C is much harder to determine. It will depend on the shape of the object, and will also depend on the speed. However, you can look up values for C that can give pretty good approximations if the body is a nice shape.

The average kinetic energy of colliding particles can be increased by increasing temperature.

The potential energy of the safe can be calculated using the formula: Potential energy = mass x gravitational acceleration x height. Plugging in the values, we get: Potential energy = 20 kg x 9.8 m/s^2 x 0.5 m = 98 Joules. Therefore, the potential energy of the safe is 98 Joules.

It remains the same. The formula for determining PE is PE = m•g•h, where m is mass in kg, g is 9.8m/s2, and h is height above the ground in meters. Temperature is not a factor in determining potential energy.

102.667 feet per second at 70 mph

This would be when you travel form one point to somewhere else and then bake again while having the same velocity when you started and when you finished.

kinetic energy = 1/2 * mass *(velocity)^2

= 1/2 * 5 * 2 * 2

= 10 joules

True. A vector quantity has both magnitude and direction, while a scalar quantity only has magnitude.

That's a big question. Do you mean how much cooling is required, or how much energy is required to cool something?

Required cooling involves calculating the heat leaks into the cooled space. This could involve solar loading, the heat leak through a wall or a window. Maybe it's the structural supports that hold up a detector at cryogenic temperatures. Typically you know something about how the amount of the heat leak varies with the temperature at its two sides. House insulation and windows have an R value that tells you how much heat leaks through as a function of the internal and external temperatures.

Once you know the load, you can calculate the amount of energy required to provide that much cooling. An air conditioner sold in the United States will have an "Energy Efficiency Rating" that tells how many BTUs/hr of cooling are produced per watt of electrical power input. So if you need 5000 BTU of cooling and your A.C. has an EER of 10, you will need 5000/10 = 500 W of electrical power to run it.

In a country that uses a sensible unit system the cooling requirement and the electrical power are both measured in Watts, so an A.C. will simply have a coefficient of performance (COP) which is the Watts of cooling per Watt of electrical power. COPs for typical air conditioners is about 3, so in the above example you would have calculated that you needed 1450 W of cooling, and with a COP of 3 you would need 480 W.

no, not really, it is 1mph less than the average walking human, so it is very slow indeed (this is not offensive)

Divide by 1.6 - a mile has approximately 1.6 kilometers.

Divide by 1.6 - a mile has approximately 1.6 kilometers.

Divide by 1.6 - a mile has approximately 1.6 kilometers.

Divide by 1.6 - a mile has approximately 1.6 kilometers.

When the rock is high up but has not been dropped yet, it has a lot of gravitational potential energy because of its position. PE = (mass) x (G) x (height) After it is dropped, the lower it goes, the less potential energy it has. That bit of missing potential energy has become the kinetic energy that it now has on account of its speed of descent. KE = 1/2 (mass) x (speed)2

No force is needed to keep an object moving. An object with no forces on it

keeps moving at a constant speed in a straight line.

If there is any force acting on it to make it slow down, then you need just enough

force to cancel the first one, in order to keep it moving.

The acceleration of the ball (after it leaves the thrower's hand) is the acceleration due to gravity, g.1 The vertical velocity of the ball at its apex is zero. The horizontal velocity is constant throughout the ball's flight; it is whatever it was at the outset of its arc.2 ---------------- 1. The acceleration due to gravity, g, is -9.8 m/s2 or -32.2 ft/s2. 2. Ignoring the effects of air resistance, which tend to slow things down.

The expression for gas pressure developed from kinetic theory relates pressure. The more familiar form expresses the average molecular kinetic energy, energy used here is limited to the translational kinetic energy of the molecules.

Yes. You could have two objects with the same final velocity (momentum, if they have mass), but having each one accelerated differently.

Imagine object A starts from 5 m/s, and is accelerated over 1 second with acceleration of 20 m/s2 to attain a final velocity of 25 m/s.

Now, imagine object B starts from 15 m/s, and gets an acceleration over 1 second of 10 m/s2 to attain the final velocity of 25 m/s.

Both end up with the same velocity, but had different accelerations.

change in velocity (v) = acceleration (a) x time (t); distance s = 1/2 a times t squared; solve for time and substitute; find a = v squared /(2s)