KCET 2019 Physics Solved Paper

(D)

→

F

= (−3

^

i

+4

^

j

)
m

→

a

= (−3

^

i

+4

^

j

)
M = 5 kg

→

a

=(

−3

5

^

i

+

4

5

^

j

) ⇒

→

a

=ax

^

i

+ay

^

j

ax=

−3

5

at t = 0

→

V0

= (6

^

i

−12

^

j

) ⇒ (Vox

^

i

−Voy

^

j

)
Vox = 6
For the body to have velocity along y-axis only, x-component of velocity should be zero i.e., Vx = 0
Vx = Vox+axt
0=6+(

−3

5

)t
6=

3

5

t
t=

6×5

3

=10s
OR
A=

F

m

= (−

3

5

^

i

+

4

5

^

j

)
u = (6

^

i

−12

^

j

) m s−1
v = u + at.
1

^

j

=(6

^

i

−12

^

j

) + (−

3

5

^

i

+

4

5

^

j

)t
=(6−

3

5

t)

^

i

(−12+

4

5

t)

^

j

−12+

4

5

t‌

^

j

=1

^

j

−

56

5

t‌

^

j

=1

^

j

t = 10 s