An object travels North at #2 m/s# for #9 s# and then travels South at #4 m/s# for #3 s#. What are the object's average speed and velocity?

1 Answer
Jun 16, 2016

Answer:

#"average speed :"v_a=2.5" "m/s#
#"average velocity :"v_a=1/3 " "m/s#

Explanation:

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#"the velocity of an object is defined as total distance covered in "#
#"unit time. Velocity is a scalar quantity. It has a magnitude but "#
#"no direction."#

#" average velocity of an object is calculated using formula:"#

#v_a=("total distance covered")/("given time interval")#

#"figure 1 shows the distance of object P"#

#"distance=AB+BC+CD+DE#

#"northward :"x_N=2*9=18 " "m"#
#"southward :"x_S=4*3=12 " "m#

#"total distance covered: " x=18+12=30 " "m#
#"given time interval : "Delta t=9+3=12 " "s#
#v_a=30/12=15/6=5/2=2.5" "m/s#

enter image source here

#"Velocity is defined as net displacement of an object in unit time"#

#"Velocity is a vector quantity. it has both a magnitude and a direction"#

#v_a=("net displacement of object")/("time interval")#

#"displacement is a vector quantity ."#

#"it is calculated either Pythagoras or cosine law".#

enter image source here

#"net displacement="18-12=4" m"#

#v_a=4/(9+3)#

#v_a=4/12=1/3 " m/s#