Question

A pendulum bob of mass 50 g is suspended from the ceiling of an elevator. Find the tension in the string if the elevator (a) goes up with acceleration $1.2m/s^2$, (b) goes up with deceleration $1.2m/s^2$, (c) goes up with uniform velocity, (d) goes down with acceleration $1.2m/s^2$, (e) goes down with deceleration $1.2m/s^2$ and (f) goes down with uniform velocity.($g=9.8m/s^2$)

Answer 1

$m=50g=0.05kg$

Here-$T-mg=ma$

$⟹T=m(g+a)$

$\left(a\right)$- $a=1.2m/s^2$

$⟹T=0.05(9.8+1.2)=0.55N$

$\left(b\right)$ $a=-1.2m/s^2$

$⟹T=0.05(9.8-1.2)=0.43N$

$\left(c\right)$ a=0

$⟹T=0.05(9.8+0)=0.49N$

$\left(d\right)$ $a=-1.2m/s^2$

$⟹T=0.05(9.8-1.2)=0.43N$

$\left(e\right)$ $a=1.2m/s^2$

$⟹T=0.05(9.8+1.2)=0.55N$

$\left(f\right)$ $a=0$

$⟹T=0.05(9.8+0)=0.49N$