Question

Erin leaves home at 11am.she cycles at a speed of 16miles per hour for 90 minutes.she stops for half an hour.erin then cycles home and arrives at 3pm
a)draw a distance time graph to show Erins journey.
b)what is Erin's average speed on the return part of her cycle​

Answer 1

Answer:

Time, Distance and Speed Conversions

To convert from km / hour to m / sec, we multiply by 5 / 18. ...

To convert from m / sec to km / hour, we multiply by 18 / 5. ...

Similarly, 1 km/hr = 5/8 miles/hour.

1 yard = 3 feet.

1 kilometer= 1000 meters = 0.6214 mile.

1 mile= 1.609 kilometer.

1 hour= 60 minutes= 60*60 seconds= 3600 seconds.

Answer 2

Given:

Speed = $16 miles/hour$

Time $=90 min$

To find:

Average speed on return journey

Solution:

We have,

The speed with which Erin leaves the house $=16miles/hour$

We know, $1 mile=1.6km$

Hence, $16mile=$ $16$ × $1.6=25.6km$

• Erin cycles for $90 min$ or $1.5hour$ . Since, she left home at $11:00AM$. After 1.5 hours that is at $12:30PM$ she shall reach the destination.

Therefore,

Distance traveled by Erin in 1.5 hours will be $=38.4km$

• We have also been given that Erin takes a 30 min break on reaching there and then leaves back for home.

• Hence, Erin begins her journey back home at $1:00PM$ and reaches home at $3:00PM$ that is total $2$ hours.

Step 1

Here,

Total distance traveled by Erin $=38.4+38.4=76.8km$

Total time taken $= 90 min+120min=210min$

                                                           $=3.5 hours$

Hence, average speed of Erin = $\frac{total-distance-traveled}{total-time-taken}$

Substituting the given values, we get

Average speed $=\frac{76.8}{3.5}=21.94km/h$

Hence, average speed of the total journey of Erin is 21.94 km/h.

Step 2

The graph of the journey is attached below.

Final answer:

Hence, Erin has an average speed of 21.94 km/h or 13.7 miles/h throughout the journey.