Question

Figure shows a plank of mass 1 kg. it is moving with Speed 2 m/s. there is the deposit of sand and the scientist drop on plank @400g/s.Find the value of F to move the blank with constant.​

Answer 1

$\huge\star{\tt{\underline{\underline{\red{Answer}}}}}\star$

$\huge{\tt{\underline{\underline{To\: find:}}}}$

Force such that plank moves with constant speed.

$\huge{\tt{\underline{\underline{Given:}}}}$

Speed of plank= 2m/s

Speed of sand drop =400g/s

$\huge{\tt{\underline{\underline{Solution:}}}}$

Velocity of sand=$\large\frac{dm}{dt}$=400 g/s

We know that

Force = Force of friction

i.e

F=F$_{f}$

F= $\large\frac{dm}{dt} \times V$ ________(1)

Speed of Sand is in gram/sec

To convert it in kilograms

Divide it by 1000

i.e

$\implies$$\large\frac{400}{1000}$

$\implies$ 0.8 kg/s

Now,

F= $\bold{\0.8 \times 2}$ From (1)

$\huge\implies$ $\huge{\boxed{\boxed{0.8N}}}$

Answer 2

Answer:

Force such that plank moves with constant speed.

$\huge{\tt{\underline{\underline{Given:}}}}$

Speed of plank= 2m/s

Speed of sand drop =400g/s

$\huge{\tt{\underline{\underline{Solution:}}}}$

Velocity of sand=$\large\frac{dm}{dt}$=400 g/s

We know that

Force = Force of friction

i.e

F=F$_{f}$

F= $\large\frac{dm}{dt} \times V$ ________(1)

Speed of Sand is in gram/sec

To convert it in kilograms

Divide it by 1000

i.e

$\implies$$\large\frac{400}{1000}$

$\implies$ 0.8 kg/s

Now,

F= $\bold{\0.8 \times 2}$ From (1)

$\huge\implies$ $\huge{\boxed{\boxed{0.8N}}}$