Why does light refract when it encounters the glass in a lens? a) because it speeds up, which causes it to bend b) because it slows down, which causes it to bend c) because it hits a dense medium, which causes it to bounce off d) because it gets absorbed, which causes it to lessen in intensity

Estimate the kinetic energy of mars with respect to the sun as the sum of two terms, that due to its daily rotation about its axis, and that due to its yearly revolution about the sun. (assume mars is a uniform sphere with mass = 6.4×10 to the power of 23 kg, radius = 3.4×10 to the power of 6 m, rotation period = 24.7 hours, orbital period = 686 days and is 2.3×10 to the power of 8 km from the sun.)