A ball is thrown from height 'h' and another from '2h'. The ratio of time taken by the two balls to reach ground is
2:1
1:2
A ball is thrown upwards, it takes 4sec to reach back to the ground. Find its initial velocity
30ms-1
10ms-1
40ms-1
20ms-1
Acceleration due to gravity at earth's surface is 'g'ms-2 . Find the effective value of gravity at a height of 32 km from sea level (Re=6400km)
0.5 gms-2
0.99 gms-2
1.01 gms-2
0.90 gms-2
Near earth's surface, time period of a satelliteis 4 hrs. Find its time period at height '4R' from the centre of earth
32 hrs
8hrs
16hrs
The earth of mass =6×1024 kg revolves around the sun with an angular velocity of 2×10-7 rad/s in a circular orbit of radius 1.5×108 km. The force exerted by the sun on earth is
6×1019 N
18×1025 N
36×1021 N
27×1039 N
The ratio of electrostatic and gravitational forces acting between electron and proton separated by a distance 5×1011m will be (charge on electron =1.6×10-19 C, mass of electron =9.1×10-31 kg, mass of proton =1.6×10-27 kg, G=6.7×10-11 Nm2/kg2 )
2.36×1039
2.36×1040
2.36×1041
2.34×1042
A.
2.36×1039
Gravitational force is the force of mutual attraction between any two objects by virtue of their masses
Coulomb force also called electrostatic force or coulomb interaction, attraction or repulsion of particles or objects because of their electric force.
Two planets are revolving around the earth with velocities v1 and v2 and in radii r1 and r2 ( r1 > r2 ) respectively. Then :
v1 = v2
v1 > v2
v1 < v2