D, I hope this is correct!
Answer:
t = 11.1 hours
Explanation:
The question says that, "A mobile advances at 20 m / s and travels a distance of 800 km. Determine the time in hours you use".
Given that,
Speed of a mobile, v = 20 m/s = 72 km/h
Distance, d = 800 km
We know that,
Speed = distance/time
So,

So, it will take 11.1 hours.
Given that.
F=3•i+4•j
And it from point (0,0)m to (5,6)m
dx=final position - initial position
dx=(5,6)-(0,0)
dx=(5,6)m
dx=5•i +6•j
Work done by the force is give by
W = F•dx
W=F•dx
Note that i•i=j•j=1 and i•j=j•i=0
Then,
W=(3i+4j)•(5i+6j)
Therefore,
W=3i•(5i+6j)+4j•(5i+6j)
W=15i•i+18i•j+20j•i+24j•j
W=15+0+0+24
W=39J
Then the work done by the force is 39 Joules
Answer:
3.75s
Explanation:
a = 8.0 m/s V = 30 m/s U = 0 m/s t = ?
t = V - U/a
t = 30 - 0/8
t = 30/8 = 15/4
t = 3.75s