psc3 054 06427 September 2013 ☈ Name:

1. During a RipStik ride in the classroom I held a ball in the palm of my outstretched hand. I was moving at a constant speed and then I suddenly stopped. The ball kept going. Using Newton's laws explain in plain English why the ball kept going.
2. _____________ Which of Newton's laws says that once moving, an RipStik continues to move at a constant velocity without any further swizzling (wiggling)?
3. _____________ Which of Newton's law governs the accelerating motion of a swizzled (wiggled) RipStik?
4. _____________ A RipStick was accelerated from a velocity of 0 m/s to 1.5 m/s in three seconds by a 52 year old instructor with a mass of 63 kilograms. Calculate the force that generated the acceleration.
5. Use the data in table two to answer the following questions on pulleys.

   Table two
   force (gmf)	load (gmf)
   20	50
   80	200
   140	350
   180	450

   1. ____________ Based on the table two data, what is the actual mechanical advantage for the pulley system?
   2. ____________ The pulley system in table two had three load lines. What is the ideal mechanical advantage?
   3. ____________ Use the preceding two questions to calculate the efficiency of the pulley system.
6. __________ A block and tackle on a crane used to lift solar panels had four load lines. What is the Ideal Mechanical Advantage for the crane based on the crane having four load lines?
7. __________ _____ If the crane with the four load line block and tackle lifts a steel beam with a mass of 800 kg, how much force will the lift motor have to produce? Use the Ideal Mechanical Advantage to make your calculation.
8. Temperatures in Celsius
   • _________°C What is the temperature of a mix of melting ice and water?
   • _________°C What is the temperature of melting solid coconut oil?
   • _________°C What is the typical daily room temperature in Pohnpei?
   • _________°C What is the temperature of the healthy living human body?
   • _________°C What is the temperature of a boiling water?
9. For the following three pulley systems, write on the picture the ideal mechanical advantage for each system:
   
10. The following xy scattergraph plots heat conduction temperature plotted as squares. The linear line is the best fit trend line mathematical model. The round circles are a mathematical model called a logistic model.
    
    Linear mathematical model: temperature = 0.40*temp+27.23
    Logistic mathematical model: $\text{temperature}=\frac{7}{(1+e^{-0.6(\text{time}-8)})}+27$
    ______________________ Which mathematical model best fits the data, the linear or the logistic model?
11. Use the following table to determine which of the materials is the best conductor of heat. The table provides information on the slope for the first nine minutes of time versus temperature data from laboratory six.
    

    Material	Slope (°Celsius/Minute)
    Rebar	1.82
    Copper	2.04
    Lead	1.53
    Zinc	0.42
    Basalt	0.049

    1. Best conductor: ___________________
    2. Why is that the best conductor?

$\text{slope m}=\frac{(\mathrm{y2}-\mathrm{y1})}{(\mathrm{x2}-\mathrm{x1})}$
$a=\frac{\Delta ѵ}{\Delta t}$
ѵ = at
$\text{Force}=\Delta \text{momentum}$
$\text{Force}=\text{mass}\times \frac{\Delta ѵ}{\Delta t}$
$\text{Force}=\text{mass}\times \text{acceleration}$
$\text{efficiency}=\frac{\text{actual mechanical advantage}}{\text{ideal mechanical advantage}}$