A particle has an initial velocity `3hati+4hatj` and an accleration of `0.4hati+0.3hatj`. Its speed after 10s is

Options

A. 7 units
B. `7sqrt2` units
C. 8.5 units
D. 5 units

Answer

B

Explanation

Here,
Initial velcoity , `vecu = 3hati+4hatj`
Acceleration , `veca = 0.4 hati +0.3 hatj`
Time , t = 10 s
Let `vecv` be velocity of a particle after 10 s.
Using , `vecv=vecu +vecat`
`:.vecv = (3hati +4 hatj )+(0.4 hati+0.3 hatj)(10)`
`= 3 hati+4hati+3 hatj =7 hati+7hatj`
Speed of the particle after 10 s = `|vecv|`
`sqrt((7)^(2)+(7)^(2))=7sqrt2` units