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It takes 4200 Joules to heat up 1 kg of water by 1 C^o. If you have a kettle with a power of 2500 Watts, how long will it takes to boil 0.8 kg of water from an initial temperature of 25 C^o to the nearest second??

Energy required calculated using the equation for specific heat capacity: mcdT = dE where m is mass, c is specific heat capacity and dT is the change in temperature.
Time taken is calculated...

Answered by Benjamin C. • Physics tutor

7574 Views

For the equation x^2 - 2x - 8 = y find: (a) The roots. (b) The y-intercept. (c) The coordinate of the turning point

(a) Several methods to do this, simplest would be to factorise the quadratic into (x - 4)(x + 2) = 0 and from here see that root occur at x = 4 and x = -2.(b) Substitute x = 0 into the equation 0^2 - 2

Answered by Benjamin C. • Maths tutor

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What is the Phillips curve?

The Phillips curve, derived by William Phillips in the 1950s, describes the relationship between unemployment and inflation. By plotting annual figures against each other, an inverse relationship was seen...

Answered by Neal S. • Economics tutor

2592 Views

Solve the simultaneous equations for x and y: 2x - 3y + 4 = 0 , x - 2y + 1 = 0.

Simultaneous equations can be solved either by substitution or elimination. Solving this by elimination:2x - 3y + 4 = 0 (1)x - 2y + 1 = 0 (2)To eliminate x, we can multiply both sides of the second equati...

Answered by Benjamin R. • Maths tutor

6572 Views

8 pens in a bag, 3 blue, 5 red. 2 taken out at random, without replacement. Probability they are the same colour?

Either both blue or both red. 'OR' rule - add probabilities.Blue - first blue and second blue - 'AND' rule - multiply probabilities. 3/8 x 2/7 (as not replaced) = 6/56 = 3/28 (multiply top and bottom)Red ...

Answered by Amy S. • Maths tutor

3350 Views