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# Maths homework help watch

1. Hi, I seem to be struggling with a question for my maths homework. The question is:

The formula KE=1/2mv^2 gives the kinetic energy (in joules) of an object with mass m kg and velocity v m/s.

A) Work out the kinetic energy of a ball with mass 1.5kg, travelling at 3 m/s. (I got 27 joules, but I'm not sure if it is correct.)

B) Draw a graph of KE against values of v between 0 and 4 m/s.

C) What is the velocity of the ball if its kinetic energy is 9 joules?

Thank you for any help in advance.
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2. If KE= given the values you would do
3. (Original post by B_9710)
If KE= given the values you would do
Ah yes I realised my mistake, can you please help with parts B and C. Thank you for the help
4. Also for B
Notice that KE meaning that it's a squared relationship between kinetic energy and speed. So what shape would this graph be?
For C you have the mass and kinetic energy, so just rearrange for v and solve.
5. (Original post by B_9710)
Also for B
Notice that KE meaning that it's a squared relationship between kinetic energy and speed. So what shape would this graph be?
For C you have the mass and kinetic energy, so just rearrange for v and solve.
Would the graph be a parabola shape because of v being squared.
6. (Original post by Fhb2001)
Would the graph be a parabola shape because of v being squared.
Yes.
7. (Original post by Fhb2001)
Would the graph be a parabola shape because of v being squared.
Yes
Very good.
8. Oh and for part C I got 2. But I'm still a little bit confused on B
9. (Original post by Fhb2001)
Oh and for part C I got 2. But I'm still a little bit confused on B
If you're still unsure about B, draw up a table and make data points and then plot them on a graph and you will see it to be a parabola (obviously only in the positive direction).
10. (Original post by B_9710)
If you're still unsure about B, draw up a table and make data points and then plot them on a graph and you will see it to be a parabola (obviously only in the positive direction).
Okay thank you for your help.
11. (Original post by Fhb2001)
Oh and for part C I got 2. But I'm still a little bit confused on B
Remember if KE=9 J
Then .
So just rearrange this.
12. (Original post by B_9710)
Remember if KE=9 J
Then .
So just rearrange this.
Is the answer close to 3.45.
13. (Original post by Fhb2001)
Is the answer close to 3.45.
14. (Original post by B_9710)
Okay thank you for your help. I understand B now as well.

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