Home > Physics > Displacement and Velocity

An object travels North at #2 m/s# for #9 s# and then travels South at #4 m/s# for #5 s#. What are the object's average speed and velocity?

Answer 1

Leo Abeyta

#"displacement="-2 m#
#"velocity="-1/7 m/s#
#"speed="19/7 m/s#

#"displacement to the north direction: "v*t=2*9=18m#
#"displacement to the south direction:"v*t=4*5=20m#

#"displacement="-2 m#

#"velocity"=("displacement")/"time"#

#"velocity=(-2)/(9+5)#

#"velocity="-2/14#

#"velocity="-1/7 m/s#

#"speed="("distance")/("time")#

#"speed="(2*9+4*5)/(9+5)#

#"speed="(18+20)/14#

#"speed="38/14#

#"speed="19/7 m/s#

By signing up, you agree to our Terms of Service and Privacy Policy

Answer 2

Sebastian Acosta

Average speed = Total distance traveled / Total time taken

Total distance traveled = (2 m/s * 9 s) + (4 m/s * 5 s) = 18 m + 20 m = 38 m

Total time taken = 9 s + 5 s = 14 s

Average speed = 38 m / 14 s ≈ 2.71 m/s

Average velocity = Total displacement / Total time taken

Total displacement = Final position - Initial position = 0 - 0 = 0 m (since the object returns to its initial position)

Average velocity = 0 m / 14 s = 0 m/s

By signing up, you agree to our Terms of Service and Privacy Policy

Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.