The Equation Gives the Position S = F(t) of a Body

question 381

Multiple Choice

The equation gives the position s = f(t) of a body moving on a coordinate line (s in meters, t in seconds) .
- $\mathrm { s } = - 9 + 3 \cos t$
Find the body's acceleration at time $t = \pi / 3 \mathrm { sec }$ .

• A) \(\frac { 3 } { 2 } \mathrm {~m} / \mathrm { sec } ^ { 2 }\)
• B) \(\frac { 3 \sqrt { 3 } } { 2 } \mathrm {~m} / \mathrm { sec } ^ { 2 }\)
• C)\( - \frac { 3 } { 2 } \mathrm {~m} / \mathrm { sec } ^ { 2 }\)
• D) \(- \frac { 3 \sqrt { 3 } } { 2 } \mathrm {~m} / \mathrm { sec } ^ { 2 }\)

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Definitions:

Fixed Ratio

A schedule of reinforcement wherein a response is rewarded only after a specified number of correct responses, leading to a high rate of responding.

Variable Ratio

A reinforcement schedule where a response is reinforced after an unpredictable number of responses, leading to high and steady response rates.

Fixed Ratio

A schedule of reinforcement where a response is rewarded only after a specified number of responses, in behavioral psychology.

Variable Ratio

A reinforcement schedule that rewards a response after a random number of responses, making it very resistant to being extinguished.