A body, under the action of a force →F=6ˆi−8ˆj+10ˆk→F=6^i−8^j+10^k, acquires an acceleration of 1 ms-2. The mass of this body must be:
1. 2 √10 kg
2. 10 kg
3. 20 kg
4. 10 √2 kg
1. | 1414 m/s and 1515 m/s |
2. | 1515 m/s and 1616 m/s |
3. | 1616 m/s and 1717 m/s |
4. | 1313 m/s and 1414 m/s |
Sand is being dropped on a conveyor belt at the rate of M kg/s. The force necessary to keep the belt moving with a constant velocity of v m/s will be:
1. Mv Newton
2. 2Mv Newton
3. Mv2Mv2 Newton
4. zero
A block BB is pushed momentarily along a horizontal surface with an initial velocity v.v. If μμ is the coefficient of sliding friction between BB and the surface, the block BB will come to rest after a time:
1. vgμvgμ
2. gμvgμv
3. gvgv
4. vgvg
A 0.5 kg ball moving with a speed of 12 m/s strikes a hard wall at an angle of 30°30° with the wall. It is reflected with the same speed and at the same angle. If the ball is in contact with the wall for 0.25 s, the average force acting on the wall is:
1. 48 N
2. 24 N
3. 12 N
4. 96 N
A tube of length LL is filled completely with an incompressible liquid of mass MM and closed at both ends. The tube is then rotated in a horizontal plane about one of its ends with a uniform angular velocity ωω. The force exerted by the liquid at the other end is:
1. | MLω22MLω22 | 2. | ML2ω2ML2ω2 |
3. | MLω2MLω2 | 4. | ML2ω22ML2ω22 |
A block of mass 10 kg10 kg is in contact with the inner wall of a hollow cylindrical drum of radius 1 m. The coefficient of friction between the block and the inner wall of the cylinder is 0.1. The minimum angular velocity needed for the cylinder, which is vertical and rotating about its axis, will be:
(g=10 m/s2)
1. 10 π rad/s
2. √10 π rad/s
3. 102π rad/s
4. 10 rad/s
A particle moving with velocity →v is acted by three forces shown by the vector triangle PQR. The velocity of the particle will:
1. | change according to the smallest force →QR |
2. | increase |
3. | decrease |
4. | remain constant |
The mass of a lift is 2000 kg. When the tension in the supporting cable is 28000 N, then its acceleration is:
(Take g=10 m/s2)
1. | 30 ms-2 downwards | 2. | 4 ms-2 upwards |
3. | 4 ms-2 downwards | 4. | 14 ms-2 upwards |
A gramophone record is revolving with an angular velocity ω. A coin is placed at a distance r from the centre of the record. The static coefficient of friction is μ. The coin will revolve with the record if:
1. r=μgω2
2. r<ω2μg
3. r≤μgω2
4. r≥μgω2