English Unlimited HTL 1, Schulbuch

Equations An equation is the mathematical way of saying: everything on the left of the equals sign is equal to everything on the right of the equals sign. Match the equations in the box to their descriptions. 1 Ke = ​ 1 __ 2 ​mv 2 Electrical power equals voltage times current 2 P = V × I Distance equals velocity times time 3 F = ma Force equals mass times acceleration 4 E = mc 2 Kinetic energy equals half times the mass times velocity squared 5 s = vt Energy equals mass times the speed of light squared TIP: Make sure you use SI units when using these equations. That way the equations will stay consistent and you will get the correct answer. Use the internet to check you know all of the units highlighted in the next exercise. Answer the questions by using the equations in 23a. 1 A car of mass 1,500 kg is accelerating at 5ms –2 . What force is being applied? N. 2 A train of mass 18,000 kg has a kinetic energy of 900,000 J. What is its velocity? ms –1 . 3 A hairdryer uses 1150 W of power. It is plugged in to the mains (230 V). What current does it draw? A. 4 Assume the speed of light is 3 ×10 8 ms –1 . A star converts 6 ×10 9 kg of mass into energy every second. How much energy does it produce per second? J. 5 A jogger is running at a steady 16 kmh –1 . How many minutes will it take her to run 36 km? mins. Write three of your own questions like those in 23b, and ask them to your partner. Solve the following problem. Then explain to a partner how you went about it. Two people cycle for two days. On the second day they cycle for 2 hours longer and at an average speed of 5 km/h faster than they cycle on the first day. If, during the two days, they cycle a total of 180 kilometres and spend a total of 14 hours cycling, what is their average speed on the first day? 23 a b 7,500 c 24 83 Language skills Extras Explore 6 Work and leisure Nur zu Prüfzwecken – Eigentum des Verlags öbv