Physics Practice – Acceleration and Simple Machines

Name: _____________________

Formulas

gravitational constant = 9.81 m/s

circumference = (π) (diameter)

speed = (distance) / (time)

velocity = (displacement) / (time)

acceleration = (change in velocity) / (time)

force = (mass) (acceleration)

force = (mass) (gravitational constant)

work = (force) (distance)

TMA = (distance out) / (distance in)

AMA = (force out) / (force in)

efficiency = [(AMA) / (TMA)] x 100%

Problem 1

A runner covers one lap of a circular track, which is 40.0 m in diameter, in 62.5 s. For that lap, what was his average speed? What was his average velocity?

Problem 2

A car traveling 70 km/hr comes to a stop at 120 m. Find the car's acceleration.

Be sure your final answer is in m/s.

Problem 3

A 900 kg crate must be lifted 10.0 m into the second story of a building. How much work must be done to move the crate? A block and tackle is used instead and an effort force of 4000 N is applied to lift the crate at a constant speed. If 25 m of rope is pulled through the block and tackle system, what is its efficiency?