An object of mass 10 kg is projected from level ground with speed 40 m/s at angle 30° with horizontal. The rate of change of momentum of object [in SI units] 1 second after the projection is [neglect air resistance]
(1) 100
(2) 50
(3) 25
(4) 75
A particle is projected horizontally with speed 20 m/s from a cliff of height 20 m. The magnitude of the velocity of particle when it reaches the ground
1. 20 m/s
2. 40 m/s
3. 20√2√2 m/s
4. Zero
A projectile is thrown with an initial velocity of 20 m/s at an angle of 60° with horizontal, then the angle of the velocity of the projectile with horizontal after time 0.732 sec is:
(1) 45°
(2) 30°
(3) 0°
(4) 15°
If ar and atar and at represent radial and tangential accelerations, then the motion of particle will be uniformly circular for :
(1) arar = 0, atat = 0
(2) arar = 0, atat ≠≠ 0
(3) arar ≠≠ 0, atat = 0
(4) arar ≠≠ 0, atat ≠≠ 0
A helicopter flies from a city A to B. The line joining A and B is along North-South direction and its length is 100 km. The speed of the helicopter is kept 100 km/h and the wind blows from West to East with a speed of 60 km/h. The time taken by the helicopter is
(1) 0.75 h
(2) 1.0 h
(3) 1.25 h
(4) 1.33 h
Four particles lie initially at the corners of a square of side length L. All the particles start to move with speed v. A moves towards B, B moves towards C, C moves towards D and D moves towards A. The distance covered by a particle till they meet is
(1) L√5L√5
(2) L
(3) √2L√2L
(4) 2L
A boat can move with a maximum speed of 10 m/s in still water. If the speed of river water is 5 m/s, then in how much minimum time the boat can cross the river of width 500 m?
(1) 100√5100√5 s
(2) 50 s
(3) 100 s
(4) 150 s
A particle is thrown at an angle of projection θθ = 45° with speed u. The average velocity of the particle during its ground to ground flight is
1. √2u√2u
2. u√2u√2
3. u2u2
4. 0
The raindrops are falling with speed vv vertically downwards and a man is running on a horizontal road with speed u.u. The magnitude of the velocity of the raindrops with respect to the man is:
1. v−uv−u
2. v+uv+u
3. √v2+u22√v2+u22
4. √v2+u2√v2+u2
A bomb is dropped from an aeroplane flying horizontally. The path of the bomb as seen by the pilot will be (neglect air friction)
(1) A straight line
(2) A parabola
(3) An ellipse
(4) A hyperbola