Question

A particle of mass 100g is thrown vertically upwards with a speed of 5 m/s. The work done by the force of gravity during the time, the particle goes up is,

• A. -0.5 J
• B. -1.25J
• C. 1.25J
• D. 0.5J

Answer 1

The correct option is B -1.25J


Gravitational force is a conservative force apply law of energy conservation
$K_A+P_A=K_B+P_B\frac{1}{2}\times \frac{100(5{)}^2}{1000}+0=0+\frac{100}{1000}\times 10\times HH+\frac{25}{20}m$
$W_{gravity}=F_{gravity}$ Hcos ${180}^{\circ }$
Since $\overrightarrow{F}$ and $\overrightarrow{H}$ are opposite in direction
=-mgH
$=-\frac{100}{1000}\times 10\times \frac{25}{20}=-1.25J$