[单选题]
On a calm day (no wind), you can run a 1ku vepl/k po7:gi87 q:500-m race at a v,0jnwo8 -ps0y/vnd mvelocity of 4.0 m/s. If you ran the same race on a day when you had a constant headwind which slows your speed by 2.0 m/s, the time it would tak0myjnvdv ,o-8s/0 nwpe you to finish would be