Q.

At t=0, a body of mass 100 g starts moving under the influence of a force (5i^+10j^) N. After 2 s its position is (2xi^+5yj^) m. The ratio x:y is _______.        [2026]

1 1 : 2  
2 2 : 5  
3 5 : 2  
4 5 : 4  

Ans.

(4)

a→=F→m=5i^+10j^0.1=(50i^+100j^)

s→=u→t+12a→t2

s→=0+12[50i^+100j^](2)2

s→=100i^+200j^=r→=2xi^+5yj^

2x=100⇒x=50  and  5y=200⇒y=40

⇒xy=54