PHYSICS EXAMPLE-test tomorrow need help please!

Question

At time t=0 s, a runner has a velocity vector, Vi--> with components Vx=2.3 m/s and Vy=0.12 m/s. At time t=2.2 s, the same runner has a velocity vector Vf--> with components Vx=2.3 and Vy=0.0 m/s. What was the runner's acceleration? (specify the direction as well)

Answer 1

At time , a runner has a velocity vector, with components and . At time , the same runner has a velocity vector with components  and . What was the runner's acceleration? (specify the direction as well).

 

[I am assuming this question is from a non-calculus-based physics course and the motion is a straight line so the average acceleration will suffice.]

 

[1] Identify the formulae, known components, unknown values, and verify units are S.I. as follows.

 

From the list, we solve for , .

 

[2] Formulate (Assuming we are dealing with a straight line):

 

 

 

[3] Analyze and finalize: We are in 2-dimensional kinematics, so we need to do each component separately.

 

From the graph, one can easily see that the acceleration in the -direction is zero and the direction is or .

 

 

NOTE* This is the “average acceleration” formula, when dealing with instantaneous, we use calculus.

 

 

 

Thus, the final acceleration, will be the magnitude of :

 

 

 

When we have a zero in the denominator, the angle is or . In this case, we want to stay within so the direction would be .

 

[4] Answer with proper units and significant figures:

 

Thus,