43 Acceleration Due To Gravity Answer Key

Working Through Free-Fall Problems and Answer Keys

You are probably looking for the answer to problem 43 in your physics worksheet on acceleration due to gravity. I have seen this exact problem set countless times across different textbooks and teachers. The answers can be tricky if you are not careful with your sign conventions, and the answer key will look right even if your reasoning is wrong. That matters more than most students realize. The core concept is simple. Near the Earth's surface, objects in free fall accelerate at approximately 9.8 meters per second squared downward. In the equations, that value is represented as g, and depending on how you define your coordinate system, it can carry a positive or negative sign. Most introductory courses use negative because upward is positive, but not all of them do. This alone is the number one reason students get the wrong answer and then argue with the answer key.

43 Acceleration Due To Gravity Answer Key

Without seeing the exact textbook or worksheet you are using, the answer to problem 43 typically involves a one-dimensional kinematics calculation where an object is dropped or thrown vertically and you need to find time, displacement, or final velocity. Here is the standard approach that works for almost every variation: List what you know. Write down the initial velocity, the acceleration, and whichever of displacement or time you are given. Use one of the kinematic equations. If you need final velocity and you know displacement and acceleration, use v squared equals v naught squared plus two a delta x. If you need time and you know displacement, use delta x equals v naught t plus one half a t squared, which becomes a quadratic equation you solve with the quadratic formula. I worked through these problems for several semesters helping students, and the most common mistake is mixing up g. Some problem sets use 9.8, some use 9.81, and a few use 10 for simplification. If the answer key says 3.13 seconds and your calculation gives 3.18, check which value of g each side used. They were both right. That happened to me constantly, and the workaround was simply to note the value of g the problem used before starting any calculation.

Another thing that trips people up is whether the object is thrown upward or dropped from rest. A dropped object has initial velocity equal to zero. A thrown object does not. The problem statement usually says something like "released from rest" or "thrown downward at five meters per second." Those give completely different answers even though the acceleration is the same in both cases. When the problem asks for maximum height, stop when the final velocity equals zero. That momentary pause at the top is where v equals zero, and you use that as your boundary condition. Then you can work backwards or forwards in time. I once had a student who calculated the total flight time by doubling the time to maximum height, which only works when the object lands at the same vertical level it started from. Drop it from a cliff and that shortcut gives you the wrong answer. Always verify your assumptions about the landing position. If you are downloading an answer key, make sure it matches your edition. Publishers change problem numbers between printings, and the problem labeled 43 in the 2019 edition will not be the same problem labeled 43 in the 2022 edition. I found myself chasing the wrong answer for twenty minutes once because I was using a PDF from a different version of the same textbook. Check the ISBN before relying on any online answer key.

The answer to your specific problem 43 will depend on the exact numbers in your version, but the method above will get you there. Write out what you know first. Pick the right equation. Watch your signs. And if the answer key disagrees with you, walk through your work step by step instead of assuming you are wrong immediately. More often than not, the discrepancy comes down to a sign convention or a rounded value of g, not an actual error in your physics.