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Learning Introductory Physics with Activities

Section 7.4 Practice - Non-constant Acceleration

Exercises Practice Activities

Activity 7.4.1. An Olympic Diver.

You are attending the Summer Olympics and have been taking data of the position as a function of time of Olympic High Divers. You have determined the following position function:
\begin{equation*} \vec{r}(t) = \left[ -Tgt - \left(T^2 g - Tv_o \right)\left(e^{-\frac{t}{T} - 1} \right) \right]\hat{y} \end{equation*}
You know \(g\text{,}\) the mass of the diver \(m\text{,}\) the time constant \(T\text{,}\) and the initial velocity of the diver \(\vec{v}_o = -v_o\hat{y}\text{.}\) Your goal is to determine the drag force as a function of time.

A*R*C*S 7.4.2. The Sprinter.

An sprinter can be modeled as having a velocity in the \(x\)-direction of \(v_x = c\left(1 - e^{-t/b}\right)\text{.}\) What is the magnitude of the sprinter’s maximum acceleration?
Solution.
Figure 7.4.1. An example of using the A*R*C*S steps.

A*R*C*S 7.4.3. The Rolling Cylinder.

A large cylinder rolls along flat, level ground. Because of substantial air resistance and varying amounts of friction, its speed decreases in a complicated way. Its speed as a function of time is \(v = at^2 + bt + c\text{,}\) where \(a = -2.00 \mathrm{~m/s^3}\text{,}\) \(b = -2.00 \mathrm{~m/s^2}\text{,}\) and \(c =12.0 \mathrm{~m/s}\text{.}\) How far does the cylinder move from \(t = 0 \mathrm{~s}\) until it comes to rest?

References References

[1]
  
“The Sprinter” adapted from Knight’s Physics for Scientists and Engineers.