Let's tackle each part of your question step by step.
Part 1:
If the safe spot is 200 feet away and Sally can run 50 feet in one second, how much faster would Simon have to be?
-
Sally's time to reach the safe spot:
- Distance = 200 feet
- Speed = 50 feet/second
- Time = Distance / Speed = \( \frac{200 \text{ feet}}{50 \text{ feet/second}} = 4 \text{ seconds} \)
-
Simon's required speed to reach Sally (who starts 75 feet away):
- Distance (to Sally) = 75 feet
- To catch Sally in 4 seconds, Simon needs to reach her in that same time.
- His speed, if he covers 75 feet in 4 seconds, would be:
\[
\text{Speed} = \frac{75 \text{ feet}}{4 \text{ seconds}} = 18.75 \text{ feet/second}
\]
-
Sally running at 50 feet/second needs Simon to be faster than 18.75 feet/second. If Simon is currently running at 20 feet/second, he would need to run at least \( 18.75 \text{ feet/second} \) to have a chance.
Part 2:
If Sally runs at 10 feet per second and the safe spot is 157 feet away, how far away would Simon have to be for Sally to win?
-
Sally's time to reach the safe space:
- Distance = 157 feet
- Speed = 10 feet/second
- Time = \( \frac{157 \text{ feet}}{10 \text{ feet/second}} = 15.7 \text{ seconds} \)
-
Simon's speed remains at 20 feet/second. We need to calculate the maximum distance from which Simon can start such that he takes longer than 15.7 seconds to reach Sally.
- Time Simon has to take = 15.7 seconds
- Distance Simon can cover in that time:
\[
\text{Distance} = \text{Speed} \times \text{Time} = 20 \text{ feet/second} \times 15.7 \text{ seconds} = 314 \text{ feet}
\]
-
Simon can start up to 314 feet away from Sally. Since Sally is starting from the safe spot (157 feet away), we want to find out how far away Simon can start from her initial position:
- The maximum distance from where Simon can start is 314 feet from Sally’s starting position (at 0 feet).
- Thus, if Sally is 157 feet away from the safe space, Simon can start \( 314 - 157 = 157 \) feet away from her.
So, for Sally to win, Simon can be at most 157 feet away from her when she starts running towards the safe space.