Projectile motion question (1 Viewer)

[irenefu]

Can someone help me with this projectile motion question - it seems really easy, but I'm really shit at this topic.

A long jump runner running at 8m/s jumps into the air, rising to a height of 0.7m. What is the length of the jump?

Thanks

 

[Demise]

We have initial velocity of 8ms-1.
a = -9.8ms-2
Change in y = 0.7

That's all I have. I'm terrible at projectile motion as well. :/

 

[Carrotsticks]

1. Let y(dot) = 0 (for max height)

2. Sub this back into y (assuming t=0, x=0, y=0) to find the general formula for maximum height.

3. Let height (y) be 0.7 and solve for initial angle.

4. You now have initial angle and the initial velocity (8m/s), so now you can find length of jump.

 

[irenefu]

The initial angle I found was 6 degrees , which is wrongg =S. Pretty sure I did something wrong, but the final answer was 5.29m . Could you try working it out?=S

 

[Carrotsticks]

Oh sorry! Totally forgot about this thread. Here is my answer. Could be off because your teacher/textbook used g=10 whereas I used g=9.8.