King Arthur is riding his horse toward a raised drawbridge of his castle with a velocity of five m/s westward.

Question

The drawbridge attendant begins to lower the drawbridge which takes 15 seconds to lower. If King Arthur is 80 meters east of the edge of the moat when the drawbridge begins to go down will the drawbridge lower in time for him to cross without stopping?

 

 

A. Yes, the drawbridge will finish lowering 1 second before King Arthur arrives.
B. Yes, the drawbridge will finish lowering 2 seconds before King Arthur arrives.
C. No, King Arthur will have to wait 1 second for the drawbridge to finish lowering.
D. No, King Arthur will have to wait 2 seconds for the drawbridge to finish lowering.

Answer 1

Given King Arthur's speed of 5m/s, it will take 80m ÷ 5m/s = 16 seconds to reach the drawbridge, by which time the drawbridge will have been lowered.

 

So, the answer is A.

 

By the way, the drawbridge does not lower itself, so the use of the personal form and the present tense in the suggested answers was inappropriate grammar.

Answer 2

Okay so let's use the speed and distance formula

 

Speed = Distance / time

 

= 80 /  5

 

= 16 sec

 

now if it takes 15 seconds to lower the bridge then (16-15=1) King Arthur would get there one sec after it lowers meaning

 

A is your answer