[2 points] In a children’s play area, a merry-go-round with…

[2 points] In a children’s play area, a merry-go-round with a moment of inertia equal to 1100 kg⋅m2 and a radius of 2.5 m rotates with negligible friction at a constant angular speed. A child of mass 53 kg initially standing still next to the merry-go-round jumps onto the edge of the platform straight toward the axis of rotation, causing the platform to slow to 1.25 rad/s. What was the original angular speed of the merry-go-round, in rad/s?

[2 points] The intensity of an earthquake wave passing throu…

[2 points] The intensity of an earthquake wave passing through the Earth is measured at two different locations on the Earth’s surface. The first measurement is 1.4×106 W/m2 at a distance of 51 km from the source. The second measurement is found to be 4.1×109 W/m2. How far from the source in kilometers was the second measurement made?