CollegeBoard SAT Physics Study Guide PT1 Q23

CollegeBoard's Book

23) This question provides us with a situation where a sled is accelerating for 3 seconds at a constant acceleration of 20 meters per second squared. Now we are prompted to find the change in speed. The key part of this question is the words constant acceleration. Since the object undergoes a constant acceleration we can use kinematic equations to solve this problem. We know the acceleration and the time, and we want to find the change in velocity. With these specifications in mind, we need to pick an equation that includes these three.

Where x is displacement, v is velocity, t is time, and a is acceleration

Let’s start with the fourth equation because it has all the variables that are given, and the only unknown will be the final and initial velocity.

Where v is velocity, a is acceleration, and t is time

Because we are not concerned with the final or initial velocity, but rather the change in velocity, let’s rewrite this equation.

Where v is velocity, a is acceleration, and t is time

Now that we have an equation that relates our 2 givens to the unknown, we can plug in values and find our answer.

Where v is velocity, a is acceleration, and t is time

Answer: D