Question

A man pushes his lawnmower with a velocity of +0.75 m/s relative to the ground. A girl rides by on her bike with a velocity of +6.5 m/s relative to the ground. What is the velocity of the girl relative to the lawnmower? A. 0 m/s B. +5.75 m/s C. +6.5 m/s D. +7.25 m/s

Answer 1

Answer:

B. +5.75 m/s

Explanation:

When there are two bodies, a and b, whose velocities measured by a third observer (in this case, the ground) are $V_a$ and $V_b$ respectively, the relative velocity of B with respect to A is given by:

$V_{ba}=V_b-V_a$

Thus, the velocity of the girl relative to the lawnmower is:

$V_{ba}=6.5\frac{m}{s}-0.75\frac{m}{s}\\V_{ba}=5.75\frac{m}{s}$

Answer 2

I took the test and got B) +5.75 m/s correct