Q15
The energy of 9800J was used to lift the 70kg weight at which height the weight was lifted?
A.
14m
AnswerB.
140m
C.
-140m
D.
-14m
Answer: Option A
Solution
Answer: Option A
Solution:
To find the height, we use the formula for gravitational potential energy:Potential Energy (PE) = m × g × h
Where:
PE = 9800 J (Energy used)
m = 70 kg (Mass of the object)
g = 10 m/s² (Acceleration due to gravity, commonly used in numerical problems)
h = ? (Height)
Substituting the given values:
9800 = 70 × 10 × h
9800 = 700h
h = 9800 ÷ 700 = 14 m
Therefore, the 70 kg object was lifted to a height of 14 metres.
Note: Options with negative height are incorrect because the object is being lifted upward, so the height must be positive.