Student Question

I need urgent physics help.

My teacher didn't explain this well. Please help with as many as u wish but if i can just get help with one at least i can figure out how to do the rest.

1. An Olympic long jumper leaves the ground at an angle of 23 degrees and travels through the air for a horizontal distance of 8.7m before landing. What is the takeoff speed of the jumper?

2. A driver springs upward from a board that is three meters above the water, A the instant she contacts the water ger speed is 8.90 m/s and her body makes an angle of 75.0degrees with respect to the horizontsl surface of the water. Dtermine her initial velocity, noth madnitude and direction.

3. A soccer player kicks the ball toward a goal that is 16.8m in front of him. The ball leaves his foot at a speed of 16.0m/s and at an angle of 28 degrees above the ground. Find the speed of the ball when the goalie catches it in fornt of the net.

4. The Javelin is launched at a speed of 29m/s at an angle of 36 degrees above the horizontal. A it travels upward, its velocity points aboce teh horizontal at an angle that decreases as time pases. how much time is required for the angle to be reduced from 36 degrees at launch to 18 degrees?



Expert Answers

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I'm going to give you a general idea of how to approach these problems. When you are working in any science, but especially in physics, write down every piece of information given in the problem--there are usually only a few types of equations you are learning about at any one time. You then look at the values you have, compare them to the equations you are working on--and amazingly enough, you will usually have all the pieces of information for one type of problem, with a missing piece that will give you your answer.  You may have to move the values around so that you get the one you are looking for by itself, but you can do it.

Now look at number 1. You have distance traveled = 8.7 m., angle of takeoff = 23 degrees, and you are looking for takeoff speed (initial velocity.) You may have to use your trig (tangents, sines, and cosines), you may have to use acceleration due to gravity, you may have to draw a picture (in fact, you probably should),to do a step before hand, but is there a formula you have that will work? Look back at the examples given in class, or in your book, and you will find something similar... Write down what you know. Find a formula that uses them. Draw a picture.

You can do this!

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