Cho phương trình chuyển động 2t^3-4t+6. Sau 2 giây đầu vật đến điểm M, và đến N mất 3 giây. Tìm vận tốc trung bình quãng đường MN, gia tốc trung bình quãng đường MN Tìm vận tốc, gia tốc tại thời gian là 7 giây

Aray of light traveling parallel to the principal axis of a concave mirror will be reflected through the mirror's

How is coal extracted from mountaintop removal mines? a. dynamite is used to create underground tunnels where miners go to extract the coal. b. dynamite is used to break apart rocks and then draglines are used to remove the broken rock and reach the coal. c. coal in mountaintops is extracted by digging strips in the landscape to reach the coal. d. placer deposits in mountain river bottoms are removed by

The sun’s mass is 2.0×10^ 30 kg, its radius is 7.0×10 5 km, and it has a rotational period of approximately 28 days. if the sun should collapse into a white dwarf of radius 3.5×10 3 km, what would its period be if no mass were ejected and a sphere of uniform density can model the sun both before and after?