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When do I use the imperfect tense and when do I use the perfect tense?

Both the perfect and the imperfect are past tenses. This means that they're both used to describe actions that have already happened.However, there are different uses for each tense. The imperfect is used...

Answered by Emilie T. • French tutor

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Two masses A and B, 2kg and 4kg respectively, are connected by a light inextensible string and passed over a smooth pulley. The system is held at rest, then released. Find the acceleration of the system and hence, find the tension in the string.

First we draw a diagram of this system (on whiteboard). Remember to label diagram correctly - the tension on both sides act towards each other.
Since B is a larger mass, we know that mass A will mov...

Answered by • Maths tutor

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A,B and C all lie on the line x^2 + y^2 = 49 where A is on the y axis, B is on the X axis and C is the mid point of the straight-line connecting A and B.

As we know that A and B are on the axis so sub in X=0 and Y=0 into the equation to solve for the co-ordinates A and B.For A 0²+y²=49y= square root of 49 = 7Do the same for B, whic...

Answered by Oliver W. • Maths tutor

3348 Views

How does free radical substitution work?

(This explanation would make use of diagrams on a whiteboard)It is useful to break this down into three steps: 1- the initiation step. Let's take the reaction between Cl₂ and CH₄.

Answered by Tom H. • Chemistry tutor

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What is the point of a derivative?

A derivative is a rate of change. For example, let y equal some function of x. Then the derivative of y with respect to x is asking how much y changes with respect to x. We can show this for any x and if ...

Answered by • Maths tutor

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