Answer: D
Explanation: During convection, heat is being transferred between substances in direct contact with each other by electro magnetic waves.
Using the molten rock to explain the convection in the earth relative to how if affects the weather condition. Here, the rock is in a molten state, rising up from the bottom of the mantle after becoming hotter and less dense from the heat of the earth's core. As the rock loses heat into the earth's crust, it become cooler and more dense,sinking back to the core. These constantly circulating cells of hotter and cooler molten rock help to heat the earth's surface.
Answer:
6.16 m/s
0.0105 m
Explanation:
Let the ground 0 for potential reference be at where the spring is compress 0.24 m. The the man would jump from a height h = 2.5 + 0.24 = 2.74 m from it. We can apply the law of energy conservation knowing that as the man jumps, his potential energy converts to kinetic energy, then finally to elastic energy:


where m = 80 kg is the man mass, g = 9.81 m/s2 is the gravitational acceleration, h = 2.74 m is the potential distance he travels, k N/m is the spring constant and x = 0.24 is the distance it compresses



Similarly at the position where it compresses by 0.12 m, it's 0.24 - 0.12 = 0.12 m far from ground 0.







When he steps gently, then his gravity force would equal to his spring force

