Posted by **lenny** on Sunday, June 17, 2012 at 3:34am.

1. A 2.5kg rock is dropped from a 350m cliff. It hits the ground with a speed of 60 m/s. What percent of its mechanical energy was lost to air resistance?

-the answer is 48%

2. A motor uses 5500J to lift a 35kg object a vertical distance of 12m. What is the efficiency of the motor?

-the answer 0.75

I need help, Thanks!

## Answer this Question

## Related Questions

- physics please help - A rock of mass 5kg is pushed over the edge of a cliff ...
- science please help and explain asap - A rock of mass 5kg is pushed over the ...
- physics - c) A 0.26-kg rock is thrown vertically upward from the top of a cliff ...
- physics - A 0.26 kg rock is thrown vertically upward from the top of a cliff ...
- physics..help PLEASE! - A 0.26 kg rock is thrown vertically upward from the top ...
- PHYSICS - A 0.26kg- rock is thrown vertically upward from the top of a cliff ...
- Physics - A boy kicks a rock off a cliff with a speed of 19.4 m/s at an angle of...
- Physics - A 0.26 kg rock is thrown vertically upward from the top of a cliff ...
- physics - A 17-kg rock is on the edge of a 103-m cliff. (a) What potential ...
- physics - a rock is dropped from a height of 15m above the ground. when it hits ...

More Related Questions