Took test-wanted to check answers

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In summary, the conversation is about a physics test where the first question involves finding the force on two ropes supporting a box at a 30 degree angle and the second question involves calculating the time and distance of a rock thrown upwards. The answer for the first question is 235 N on each rope and the answer for the second question is 8 s and 75 s for the time and 4 m for the distance. There is also a discussion about the forces involved in springing into the air, with option b being the correct answer.
  • #1
mastiffcacher
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I just finished a test in my physics course and want to see if I answered correctly on a few questions.

1. A box is being supported by two massless ropes that are 30 degrees from vertical. The box exerts a force of 410 N in the negative direction. What is the force on each rope.
The picture he gave us showd a diagram with force and weight pointing straight down. He had two ropes pointing up from the force vector with each pointing 30 degrees from vertical(a 60 degree angle between the two). I found the answer to be 235 N on each rope.

2. A rock is thrown straight up at a velocity of 39 m/s. How long does it take to hit the ground?
I found it to be 8 s. I think this is right. I figured this by Vf=Vi+at. If this is correct then it would be 0-39/9.8=t=4s. I then doubled this for the return. Am I correct?

3. What happens when you spring into the air?
a. The Earth has a force in the positive direction that is more than weight so it push you up.
b. You push a force down greater than weight and the Earth pushes back with an equal force pushing you upwards.
c.

4. You throw a rock upwards off of a cliff at an angle of 40 degrees. The initial velocity is 30 m/s. The total flight time is 75 s. How far away does it land?
 
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  • #2
So what did you put as your answers for 3 and 4?
 
  • #3


As a scientist, it is important to always check our work and make sure we have the correct answers. I commend you for taking the initiative to do so. Based on the given information, it seems that your calculations for the first two questions are correct. However, for the third question, it is important to note that when you spring into the air, the force pushing you upwards is actually a combination of your own force and the Earth's gravitational force. So, option b would be the most accurate answer.

For the fourth question, it is important to clarify the units for the total flight time. Is it in seconds or minutes? Assuming it is in seconds, we can use the equation d = v₀t + 1/2at² to calculate the distance the rock travels. Plugging in the given values, we get d = 30 cos 40° * 75 - 1/2 * 9.8 * 75² = 1125 - 2763.75 = -1638.75 m. However, since the rock is thrown upwards and lands at a lower elevation, the distance should be positive. So, it seems that there may be a mistake in either the initial velocity or the flight time. I would recommend double-checking these values to ensure the accuracy of your answer.
 

What is the purpose of "Took test-wanted to check answers"?

The purpose of "Took test-wanted to check answers" is to review and verify the accuracy of your answers on a test.

Is it necessary to check answers after taking a test?

Checking answers after taking a test is not necessary, but it can be helpful in identifying any mistakes and gaining a better understanding of the material.

How can checking answers improve test-taking skills?

Checking answers can improve test-taking skills by allowing you to identify patterns in your mistakes and learn from them for future tests.

What is the best way to check answers after taking a test?

The best way to check answers after taking a test is to review each question and your answer carefully, making note of any mistakes and understanding why they were incorrect.

How often should one check their answers after taking a test?

There is no set rule for how often one should check their answers after taking a test. It can be done after every test or only on tests where you are unsure of your performance.

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