Sand is being dropped on a conveyer belt at the rate of 2 kg per second. The force necessary to keep the belt moving with a constant speed of $3 \mathrm {~ms} ^ { - 1 }$ will be (1) 12 N (2) 6 N (3) zero (4) 18 N
Sand is being dropped on a conveyer belt at the rate of 2 kg per second. The force necessary to keep the belt moving with a constant speed of $3 \mathrm {~ms} ^ { - 1 }$ will be\\
(1) 12 N\\
(2) 6 N\\
(3) zero\\
(4) 18 N