Một chất điểm chuyển động trên đường tròn bán kính 5m từ trạng thái đứng yên, nhanh dần đều với gia tốc góc bằng 2 rad/s2. Sau 20 giây vật có vận tốc m/s và gia tốc hướng tâm m/s2

Asmall metal bar, whose initial temperature was 10° c, is dropped into a large container of boiling water. how long will it take the bar to reach 70° c if it is known that its temperature increases 2° during the first second? (the boiling temperature for water is 100° c. round your answer to one decimal place.) sec how long will it take the bar to reach 98° c? (round your answer to one decimal place.)

Adiver in midair has an angular velocity of 6.0 rad/s and a moment of inertia of 1.2 kg·m2. he then pulls is arms and legs into a tuck position and his angular velocity increases to 12 rad/s. the net external torque acting on the diver is zero. what is his moment of inertia in the tuck position?

Suppose a wire with a current is pushed upward by a magnetic field. how would the wire move if the direction of the current reversed? explain your answer.