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# Power and Thermal Velocity question.. watch

1. Hi all,

I am doing a SKE in Chemistry at the moment but have to do some physics (which I hate and I am not good at, luckily I won't have to teach it)...

The two questions are:

1. Using a suitable equation of motion calculate the terminal velocity (velocity just as the object hits the ground) of an object that falls (from rest) from a height of 200m.(assume that g=10m/s2)

2. A 10kg metal block is lifted by 20 meters by a motor in 8 seconds. Calculate the power of the motor (assume g = 10m/s2)

I don't even know where to start?

Thanks to anyone who can help in advance
2. (Original post by Lambert87)
1. Using a suitable equation of motion calculate the terminal velocity (velocity just as the object hits the ground) of an object that falls (from rest) from a height of 200m.(assume that g=10m/s2)
This can be solved via an energy approach: all of the GPE of the object is converted into KE just as it hits the ground. So make an equation, and then solve the equation:

Taking the zero level of GPE to be at the ground, we have and

Alternatively, if you know that all objects fall with the same gravitational acceleration, you can use one of the SUVAT equations directly. The first approach will give you the same equation, though.

2. A 10kg metal block is lifted by 20 meters by a motor in 8 seconds. Calculate the power of the motor (assume g = 10m/s2)
By definition, .

How much energy must the motor transfer to the block, in raising it by 20 m? (Hint: see the first question).

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