![]() ![]() So, we know the force in newtons and the distance the ball has travelled. This requires 1 newton of force and over a period of a second, the ball travels 0.5m. The ball begins in a stationary position and accelerates at 1m/s² for 1 second. Also, let’s assume that the ball weighs 1kg to keep the calculations simple. To simplify the scenario, let’s pretend that there is no gravity, there is no air and so no other forces are acting upon the ball. We will move a stationary 10-pin bowling ball 0.5 metres in a straight line in space. We still refer to horsepower when talking about vehicles and machinery, and in case you were wondering, 1 horsepower = 746 watts. Power is the rate at which energy is transferred, which also means the rate of doing work. In fact, energy is the ability to do work! Work and energy have a close relationship because energy is required to do work, which is why the SI units of energy and work are joules. Remember, this is the norm in the universe and objects only slow down on Earth due to friction. In fact, this is well explained by Newton’s 1st Law of Motion which is often stated as “Objects in motion, stay in motion and objects at rest stay at rest, unless acted upon by a net external force”. As we know from our everyday experience, stationary objects don’t move without influence. As we know from GCSE Physics, displacement is the movement of an object in a straight line. How far did they fall? (in km) Your answer should include: 4 / 4kmĭ = E ÷ F = 3,322,000 J ÷ 833 N = 4000 m or 4 Km.Another way of understanding the concept of work is to think that work done equals displacement whilst a force is being applied. Work done = 50 KJ ≣ 50,000 J (Joules, not Kilo-Joules, are the SI unit) A parachutist is pulled to the Earth with a weight of 833 N and 3332 KJ of work are done in the fall. ![]() If a force of 300 N is applied to a car, how far will it move if the work done to the car was 50 KJ? For the value you have been asked to find put a ‘?’ (This is very useful if you are dyslexic)Īs you read the question, every time you come across a number, stop and write down what the quantity is and the value in the margin of the paper or on a scrap piece of paper so you end up with a list. If like many people you find it hard to pick out the numbers from the sentence try this simple trick. Check what units have been given in the question and change them if you need to. All calculations should use SI units such as meters, seconds, etc. If a force of 300 N is applied to a car,how far will it move if the work done to the car was 50 KJ?Į= Fd ∴ d = E ÷ F = 50,000 J ÷ 300 N = 166.67 mīefore performing any calculations in an exam always check the units to be used. (recall distances must be in meters when performing calculations). Weight = mass x gravity = 8 x 9.8 = 78.4 N _Ī shopping trolley is pushed with a force of 250 N for a distance of 20m, calculate the work done to the trolley.Ī sports bag has a mass of 8 Kg and is lifted into the boot of a car from the ground, a height of 85cm.įorce required to lift the bag is equal to the weight of the bag (pull of gravity on the mass). Note: In this exam all forces will act in the same direction as the movement of the object. The work done to the cars (and the passengers) by the motor will be equal to the gravitational potential energy at the top of the slope (if we ignore frictional heat loss). Work is a measure of the energy transferred to an object, as such it can be measured in Joules.Įxample: A roller coaster is pulled up the first part of a track by the electrical motor acting against gravity. For an object being lifted vertically upwards the upwards lifting force is equal to the weight of the object (weight is the pull of gravity on a mass). The force to move the object and the distance over which this force was applied to the object.įorces can be measured using a Newton (or Force) meter and distance by any suitable device or ruler. To measure the work done in moving an object, two quantities need to be measured. Work is a measure of the amount of energy transferred to a object when it is moved by a force. ![]() Work in physics has a very specific meaning, which is very different compared to the use of the word, ‘work’ in everyday language. Triple: Light & the Electromagnetic Spectrum. ![]()
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