Question

The energy of $4900J$ was expended in lifting a $50kg$mass. The mass was raised to a height of

• A. $10m$
• B. $98m$
• C. $960m$
• D. 245000

Answer 1

The correct option is A

$10m$

Step 1: Given

Energy$E=4900J$

Mass$m=50kg$

Height$h=?$

Step 2: Calculate the potential energy

The potential energy in terms of mass, acceleration due to gravity, and height of the mass,

$$\begin{gathered} \Rightarrow E=mgh \\ \Rightarrow 4900=50\times 9.8\times h \\ \Rightarrow 4900=490\times h \\ \Rightarrow h=\frac{4900}{490}=10m \\ \Rightarrow h=10m \end{gathered}$$

Thus, we say that the mass was raised to the height of $10m$.

Hence, option A is the correct answer.