Answer: 1.3 m
Step-by-step explanation:
Given that,
power of motor lift = 21 watts
Mass of package (m) = 10 kg
height (h) = ?
Time (h) = 6 seconds
Since power is the rate of work done per unit time i.e Power is simply obtained by dividing work by time. Its unit is watts.
i.e Power = work / time
[since work = force x distance,
& force = mass x acceleration due to gravity (g)]
Then, Power = (mass x acceleration due to gravity x height) / time
Recall that g has a value of 9.8 m/s²
I.e Power = mgh / t
21 watts = (10 kg x 9.8 m/s² x h) / 6s
21 watts = (98 kgm/s² x h) / 6s
Cross multiply
21 watts x 6s = 98 kgm/s² x h
126 watts•s = 98 kgm/s²•h
Divide both sides by 98 kgm/s²
126 watts•s / 98 kgm/s² = 98 kgm/s²•h/ 98 kgm/s²
1.286 m = h
(Round the 1.286 m to the nearest tenth as 1.3 m)
Thus, the package can go 1.3 metres high