Satellites

Q.

A body of mass m is situated at a distance 4R above the earth's surface, where R is the radius of earth. How much minimum energy be given to the body so that it may escape

1. mgR

2. 

3. 

4. 2mgR

Q. A simple pendulum with a metallic bob has a time period 10 s. The bob is now immersed in a non-viscous liquid of density 1/3 that of metallic bob. The time period of the same pendulum becomes- (1) 10 s (2) 10/root2 s (3) 10root3/2 s (4) 10root3 s

Q. two particles having mass M and m are moving in a circular path having radius R and r if their time periods are same then ratio of their angular speed is

Q. If the string of a conical pendulum makes an angle θ with horizontal, then square of its time period is proportional to (1) sinθ (2) cosθ (3) tanθ (4) cotθ

Q.

Two satellites of masses $m_1$ and $m_2(m_1>m_2)$ are revolving round the earth in circular orbits of radius $r_1$ and $r_2(r_1>r_2)$ respectively. Which of the following statements is true regarding their speeds $v_1$ and $v_2$?

1. $v_1=v_2$

2. $v_1<v_2$

3. $v_1>v_2$

4. $\frac{v_1}{r_1}=\frac{v_2}{r_2}$

Q.

Can gravitational potential energy negative?

Q.

Six stars of equal mass m are moving about the centre of mass of the system such they are always on the vertices of a regular hexagon of side length a. Their common time period will be

1. 

2. 

3. None of these

4. 

Q. Choose the correct alternative: (a) If the zero of potential energy is at infinity, the total energy of an orbiting satellite is negative of its kinetic/potential energy. (b) The energy required to launch an orbiting satellite out of earth’s gravitational influence is more/less than the energy required to project a stationary object at the same height (as the satellite) out of earth’s influence.

Q. Two satellites of mass m and 2m are revolving in two circular orbits of radii r and 2r around an imaginary planet , on the surface of with gravitational force is inversely proportional to dis†an ce from its centre. The ratio of orbital speed of satellites is (1) 1:1 (2) 1:2 (3) 2:1 (4) 1:\sqrt2

Q. 39. If the length of a clock pendulum increases by0.2% due to atmospheric temperature rise, then theloss in time of clock per day is(1) 86.4s(3) 72.5(2) 43.2 s(4) 32.5 s

Q. A block of mass m is at rest on a rough inclinedplane of angle of inclination θ . If coefficient offriction between the block and the inclined plane isμ , then the minimum value of force along the planerequired to move the block on the plane is(3) m glucose+ sin0\rbrack(4) mg\lbrack sine-μ o0se\rbrack ldo dawn on

Q. A toy rocket of mass 0.1kg has fuel of mass 0.02kg which burns out in 3sec. Starting from rest on a horizontal smooth track, it gets a speed of 20 m/s when fuel is burned out. What is the approximate thrust of the rocket? What is the energy content per unit mass of fuel?

Q. A wave moves with speed 300m/s on a wire which is under a tension of 500N.Find how much the tension must be changed to increase the speed to 360m/

Q.

The orbital angular momentum of a satellite revolving at a distance r from the centre is L. If the distance is increased to 16r , then new angular momentum will be

1. $16L$

2. $64L$

3. $\frac{L}{4}$

4. $4L$

Q. 28. What is the displacement between origin and maximum height of of projectile during its motion

Q. A simple pendulum with iron bob has a time period T. The bob is now immersed in a non-viscous liquid and oscillated. If the density of liquid is1/12 th that of iron, then new time period will be

Q. The radius of the orbit of a geosynchronous sateiliteis 36000 km. Then the period of revolution of a satellite with its orbital radius 9000 km would be

Q. A shell in a flight explodes into 4 in parts Why cant potential energy and kinetic energy be conserved?? Can they be constant??

Q. a particle is moving in a circle of radius R =3 m with an angular speed 2 radian per second

Q. Two stars each of one solar mass $(=2\times {10}^{30}kg)$ are approaching each other for a head on collision. When they are a distance ${10}^{9}km$, their speeds are negligible. What is the speed with which they collide ? The radius of each star is ${10}^{4}km$. Assume the stars to remain undistorted until they collide. (Use the known value of G).

Q.

Two satellites of masses 3m and m orbit the earth in circular orbits of radii r and 3r respectively. The ratio of their orbital speeds is

1. $1$

2. $\sqrt{3}$

3. $\frac{1}{2\sqrt{3}}$

4. $\frac{1}{3}$

Q. A simple pendulum has time period T1 when it is on earths surface and T2 when it is taken at height 2R above the earth surface calculate T2/T1.(R is the radius of earth

Q. a stone is allowed to fall from top of a building and covers half of the height in last second of its motion . the time taken by stone to reach the bottom of building is a)2 sec b)1 sec c) 2+\sqrt2 d)2-\sqrt2

Q. In reference to a frame e fixed to Sun is the gravitational force acting on the planet is equal to centripetal force m v²/r, where v is speed of planet and r is distance between sun and planet

Q.

A satellite can be in a geostationary orbit around the earth at a distance r from the center. If the angular velocity of the earth about its axis doubles, a satellite can now be in a geostationary orbit around the earth if its distance from the center is,

Q. why is gravitation independant of medium

Q. what is gravitation

Q. A spacecraft travels from earth to moon & then on return trip from moon to earth. From earth to moon it requires $f_1$ units of fuel & from moon to earth it requires $f_2$ units of fuel, then

1. $f_1<f_2$
2. $f_1>f_2$
3. $f_1=f_2$
4. Cannot say as it depends upon mass of the space craft

Q. The minimum and maximum distances of a planetrevolving around sun are r and R. If the minimumspeed of planet on its trajectory is vo, its maximumspeed will beVoRVor22(3) 24) R2

Q. The magnitude of gravitational potential energy of satellite & earth is -12 kJ if zero potential energy is taken at infinite separation. The K.E of satellite is

1. 6 kJ
2. 12 kJ
3. 24 kJ
4. None