Success! When deciding which form of an equation to use, always consider which variables you’re given, and look for the form of the equation that contains those variables. By substituting and rearranging, you can get Potential energy is increasing, so you can write ∆E = mg∆h. Therefore, P = ∆E/∆t is likely to be the most helpful form of the equation for power. You also know that the object is moving upward and is therefore gaining potential energy. Look at what you do have: information about power, time, and mass. While you know that the object is moving upward, you don’t have any information about its velocity, so P = Fv may also not seem very helpful. Do you write down P = IV? Or do you write P = Fv? What about P = ∆E/∆t? Here, you’re not dealing with current or voltage, so P = IV will not apply. In the example discussed above, for instance, the question involves power. In some situations, though, you might be dealing with a quantity that has more than one formula. Does the question mention acceleration? Write down F = ma. Does the question mention two objects colliding? In that case, you’ll likely need the formula for momentum. Fortunately, the AP Physics exam does provide you with a formula sheet, but even so, finding the right formula can be tricky.įirst, consider the information given in the problem.
This last step is particularly vital, even if you don’t yet know how you’re going to use the formulas. Write down any relevant formulas, and plug in what you know. In the question above, you could add in the following information:ģ. If you’re working a question that involves forces, for example, you should draw force vectors in your diagram. This includes any numbers given in the problem, as well as information that you have from your own knowledge.
Once you have a solid understanding of what the situation looks like, you can add in everything you know. Your picture of the situation doesn’t have to be particularly artistic or detailed, and might look like this: If the crane operates for 20 s, how high will it lift the object in this time? Consider the problem below:Ī crane provides 1500 W of power to lift an object with a mass of 60 kg.
Otherwise, you’re trying to both imagine the situation at hand and work out the math, and the fewer tasks you need to juggle mentally, the better. Many problems on the exam already contain pictures or diagrams, but if you’re attempting a problem that doesn’t include any kind of visual representation, draw one. While study and practice are undeniably indispensable to your success on the test, there are three steps that you can take if you find yourself feeling baffled. You know the feeling: your mind goes blank, your stomach churns, your palms begin to sweat, and you find yourself staring, motionlessly, at the page. It’s not surprising, therefore, if you find yourself getting stuck on some questions on this famously difficult exam.
0 kommentar(er)
