Difference between energy and work

Learn difference between kinetic energy and W.

• You can do the work W with the formula W = F _* Calculate s if the force F and the path s have the same direction. The force must remain the same during the entire journey. The unit for work is one joule (J), which corresponds to one Nm.
• In contrast, if a body does not move in the direction of force, for example if you pull a handcart with a drawbar, then the angle between the direction of force and direction of travel must be taken into account. In this case you use the formula W = F _* s _* cos α.
• Braking the car by moving the drawbar in the opposite direction, use the same formula, but the value of the work will be negative.
• Because you have done work on the handcart, it is now able to do work itself, which means that it can continue to roll on its own. This supply of stored work is called
  instagram viewer
  energy (E). It is also calculated in joules (J).
• Remember that a body's energy increases when the work is positive and decreases when the work is negative.


Convert joules to newtons - a guide

In order to perform daily duties, work must be done. To work ...

• If you want to calculate the time in which work was done, use the formula for the performance (P). It reads: P = W / t with the unit watt (W).
• If you bring a body with a certain mass (m) to a speed (v) with a constant force (F), this body contains the kinetic energy E through this work_k. It is also called kinetic energy and can be expressed by the formula E._k = 1/2 mv² can be calculated.
• Use the formula W to determine the acceleration work required for the speed difference_a = 1/2 m (v² - v₀²), where v₀ is the initial speed and v is the final speed.

How to find E_p and the potential energy

• In contrast to kinetic energy, when a body is lifted vertically at constant speed and the resulting force F, there is positional energy. It is also called potential energy and can be expressed using the formula E._p = mgh can be calculated. Note that with this formula g the falling speed of 9.81 m / s² and h is the height.
• To bring the potential energy into the body through lifting, use lifting work, which is expressed by the formula W._H = mg (h - h₀) is calculated.
• Stretching a coil spring also requires a tensile force. The work required for this is contained in the spring as tension energy. You calculate them with the formula E._s = 1/2 Ds², where s describes the distance the spring travels while stretching, and D is the spring constant.
• The work involved in tensioning the spring is called tensioning work and is expressed using the formula W._s = 1/2 D (s² - s₀²) calculated.
• The calculation of the frictional work that has to be expended on a braked body in order to move it can be given by the formula W_r = μ F_nCalculate s, where μ is the coefficient of friction and F_n is the normal force with which the body presses perpendicularly on the surface.
• The friction creates thermal energy through the mechanical energy. Note that in contrast to the other forms of energy, the thermal energy cannot be completely converted back into mechanical energy. The law of conservation of energy applies to all other forms of energy.