Search our library of A Level questions

Top answers

All subjects

A Level

Show, using the focus-directrix property for an ellipse, that PS +PS'=2a where P is a point on the ellipse and S and S' are the two foci.

The focus diretrix property for an ellipse is PS/PD=e. Now this is also the case for the other directrix and focus, so PS'/PD'=e. Now we can rearrange these equations to find a formula for PS +PS', PS +PS...

Answered by Daniel L. • Further Mathematics tutor

11581 Views

A phone is knocked off a table 800cm of the ground. If the phone is 650g a) what is the gravational potential of the phone? b)what speed will the phone hit the floor at? c)How long will it take for the phone to hit the floor?

UNITS - SI UNITS: 800cm --> 0.8m 0.65kg

a) Ep= mg(change) height

Ep=0.65kg * 9.81m/s² * 0.80m

Ep=5.10 Joules (J)

b) Gravational Potential = Kinetic energy

Answered by Julia J. • Physics tutor

1785 Views

Find the exact solutions for 4 − x^2 = |2x − 1|

x=-1

x=-1+6^0.5

Answered by Shroya V. • Maths tutor

5972 Views

What is a confidence interval?

Using the normal distribution, we can estimate a range of values which we expect to contain the mean. For example, if we take a sample of 30 students height, we can estimate the mean height of students in...

Answered by Alexander R. • Maths tutor

4495 Views

Do global superpowers reflect the 'north-south' divide?

Global superpowers can be defined as states which are powerful on the global stage, both explicitly through their role in global institutions such as the UN and implicitly through their influence. Since t...

Answered by Phoebe R. • Geography tutor

3513 Views