Rj and Joshua are running in the fun run. Rj runs at 7kph and Joshua at 5kph. if they start at the same time, how long will it be before Rj is 1/4 km ahead of Joshua?
since the speed difference is 2 km/hr,
(1/4 km) / (2 km/hr) = 1/8 hr
To find out how long it will be before Rj is 1/4 km ahead of Joshua, we need to determine their relative speed.
The speed of Rj is 7 kph, and the speed of Joshua is 5 kph.
So their relative speed is the difference between their speeds: 7 kph - 5 kph = 2 kph.
To calculate the time it takes for Rj to be 1/4 km ahead, we can use the formula:
Time = Distance / Speed.
Let's calculate the time:
Time = 1/4 km / 2 kph
To simplify the calculation, we need to convert 1/4 km into a decimal form:
1/4 km = 0.25 km
Now we can calculate the time:
Time = 0.25 km / 2 kph
Time = 0.125 hours
Since we want to express the time in minutes, we need to convert hours to minutes:
1 hour = 60 minutes
So:
0.125 hours x 60 minutes/hour = 7.5 minutes
Therefore, it will take approximately 7.5 minutes before Rj is 1/4 km ahead of Joshua.
To find out how long it will take for Rj to be 1/4 km ahead of Joshua, we need to determine their relative speed and calculate the time it takes for them to have a 1/4 km distance between them.
First, let's find the relative speed of Rj compared to Joshua. Since Rj runs at 7 kph and Joshua at 5 kph, Rj's speed relative to Joshua can be calculated by subtracting Joshua's speed from Rj's speed:
Relative Speed = Rj's Speed - Joshua's Speed
= 7 kph - 5 kph
= 2 kph
Now we know that Rj is 2 kilometers per hour faster than Joshua.
To calculate the time it will take for Rj to be 1/4 km ahead of Joshua, we can use the formula:
Time = Distance / Speed
Since we want to find the time it takes for Rj to be 1/4 km ahead of Joshua, we have:
Time = 1/4 km / Relative Speed
= 0.25 km / 2 kph
Now we divide 0.25 km by 2 kph:
Time = 0.25 km / 2 kph
= 0.125 hours
To convert hours to minutes, we multiply by 60:
Time = 0.125 hours * 60 minutes/hour
= 7.5 minutes
Therefore, it will take approximately 7.5 minutes for Rj to be 1/4 km ahead of Joshua.