Question

Convert a) 2873540 seconds to months, assuming there are 30 days per month b) 215 km/hr to m/sec c) 58.2 km/sec to mph d) 68.45 lbm/ftto kg/m3 e) 1.362 g/cmº to lbm/ft?

Answer 1

a. 2873540 seconds are 1.11 days.

b. 215 km/hr= 59.72 m/sec

c. 58.2 km/sec = 93.66 mph

d. 68.45
`(lbm)/(ft^(3) )`= 1097.135
`(kg)/(m^(3)  )`

e. 1.362 g/cm= 0.0915 lbm/ft

Step-by-step explanation:

To convert units, the simplest is to use The Rule of Three, which allows you to work with proportions, such as these cases.

In the case a) : To convert to months, you must first convert to minutes.

60 sec ⇒ 1 minute

2873540 sec ⇒ x

`x=(2873540*1)/(60)`

So x=47892.33 minutes

In the same way, and knowing that 1 hour is 60 minutes, you can know that:

60 minutes ⇒ 1 hour

47892.33 minutes ⇒ x

`x=(47892.33*1)/(60)`

x=798.205 hours

Now, knowing that 1 day is 24 hours and applying the same method, you can know that: 798.205 hours= 33.26 days

And finally, knowing that 1 months have 30 days and applying the same method, you can know that: 33.26 days= 1.11 days

So, you can say that 2873540 seconds are 1.11 days.

Case b):

In first place, you can convert km to m:

1 km ⇒ 1000 m

215 km ⇒ x

x=
`798.205=(215*1000)/(1)`

x= 215000 m

And now you have to convert the hour to minutes:

1 hour ⇒ 60 minutes

And: 1 minute ⇒ 60 seconds

60 minutes ⇒ x

`x=(60*60)/(1)`

x=3600 seconds

So 1 hour= 3600 seconds

Now both unit changes are combined.

`215 (km)/(hr) = (215000 m)/(3600 sec)`

The result is 215 km/hr= 59.72 m/sec

Case c):

To convert from kilometer per second to kilometer per hour, and knowing that 1 hour= 3600 seconds (case b), you:

3600 sec ⇒ 1 hour

1 sec ⇒ x

So 1 sec= 0.00027 hr

By multiplying the value in kilometers per second by 0.00027, you get 0.0162 km/h

Now you know that 1 km= 0.621371 milla, so using The Rule of Three you can do the unit conversion and you get that 58.2 km/sec = 93.66 mph

Similar to the previous cases, case d) and e) can be resolved.

You have to know that:

1 lbm ⇒ 0.4536 kg

1
`ft^(3)` ⇒ 0.0283
`m^(3)`

1 lbm ⇒ 453.6 g

1 ft ⇒ 30.48 cm

So, the results are:

68.45
`(lbm)/(ft^(3) )`= 1097.135
`(kg)/(m^(3)  )`

1.362 g/cm= 0.0915 lbm/ft