His model was not accepted by ancient philosophers because they said (1) if earth is rotating, why can't we feel the the motion of earth, and (2) if earth is orbiting the sun, then the position should be different when it is on opposite side of the sun (parallax effect).

Aballet student who learns with the of his instructor is demonstrating learning.

Astudent pushes on a 20.0 kg box with a force of 50 n at an angle of 30° below the horizontal. the box accelerates at a rate of 0.5 m/s2 across a horizontal floor. what is the value of the normal force on the box? 200 n 243 n 156 n 225 n

Henry, whose mass is 95 kg, stands on a bathroom scale in an elevator. the scale reads 830 n for the first 2.4 s after the elevator starts moving, then 930 n for the next 2.4 s. part a what is the elevator's speed 4.8 s after starting? express your answer with the appropriate units.