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A car of mass 1000 kg is travelling at 15 m/s. The driver applies the brakes for 4 seconds, slowing the car to 5 m/s. What is the average power output of the brakes over the 4 seconds? Assume there are no other forces acting on the car.

Kinetic Energy, EK=(1/2)mv². Energy is conserved, so the work done by the brakes, W, must be equal to the change in kinetic energy of the car, ∆EK. Therefore: W = ∆EK = (1/2)1000(15

Answered by Adam H. • Physics tutor

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i) The point A on a graph is (6,-7), and point B is (3,5). Calculate the equation of the straight line that passes through both A and B. ii) Does the line pass through the point C (-2,26)?

i) Gradient (m) = ∆y/∆x. Therefore: m = (5-(-7))/(3-6) = (12)/(-3) = -4. Intercept (c) = 5-(3*(-4)) = 5+12 = 17. Therefore: y = -4x+17 ii) x = -2, y = 26. -4(-2) + 17 = 25. 25≠26, therefore the line does ...

Answered by Adam H. • Maths tutor

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How do I solve simultaneous equations? eg 1) 4x = 16 - 2y and 2) 3x + y = 9

With simultaneous equations it's important to write down all your working so you keep everything clear in your mind and don't get confused. Start by putting all the x and y of both equations on one side. ...

Answered by Sarah A. • Maths tutor

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The length of a rectangle is five times the width. The area of the rectangle is 180cm^2. Work out the width of the rectangle.

Lets start off by calling the width of rectangle 'w'. The length of the rectangle is 5 times the width, or '5w'. The area of a rectangle can be worked out by multiplying the length by the width, i.e. 5w x...

Answered by Hannah W. • Maths tutor

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Find the gradient of the line on which the points (1,3) and (3,4) lie and find the y-coordinate of the line at x = 7.

The gradient is m = (y1-y0)/(x1-x0) = (4-3)/(3-1) = 1/2. So the equation of the line is y= x/2 + c where c is a constant. To find the constant, c, we will input one of the given coordinates (1,3). This sh...

Answered by Ryan L. • Maths tutor

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