<span>Tectonic plates move because they are floating on top of the liquid mantle. The mantle itself moves due to convection currents: hot rock rises, gives off some heat, then falls. This creates vast swirls of moving liquid rock under the crust of the earth, which jostles the plates of crust on top.
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F=ma
8480=26.5m
m=8480/26.5
m=320
The mass of the cart is 320kg.
Answer:
52,360,000km
Explanation:
To solve this problem you use a conversion factor.
By taking into account that 1UA = 1.496*10^{8}km you obtain:

hence, 0.35UA is about 52,360,000km. This is the least distance between Mars and Earth
The pressure exerted by the block on the table is given by:

where W is the weight of the box, and A is the bottom surface area of the box.
The weight of the box is: 
Substituting into the first equation, we find the pressure:

The answer would be C. It will decrease with descent. Hope this helps!