what is focal length of double concave lens kept in air with two spherical surface of radii R1=30 and R2=60. Take refractive index of lens as n=1.5

How do you tell if someone actually cares about you? and just say they do?

Acorporation gives out its profits as dividends paid to whom?

One soccer player (a) is moving at 4 km/h when she kicks the ball while another soccer player (b) is moving at 8 km/h. what statement accurately compares their kinetic energy if they have the same mass? a) both soccer players have the same kinetic energy. b) player b has twice the kinetic energy of player a. c) player b has four times the kinetic energy of player a. d) their kinetic energy can't be compared without knowing their mass.