Question

# The time taken by a block of wood (initially at rest) to slide down a smooth inclined plane 9.8 m long (angle of inclination is 30°) is

Solution

( Rightarrow S=u t+frac{1}{2} a^{2} )

( Rightarrow 9.8=0+frac{1}{2} times g times sin 30 t^{2} )

( Rightarrow 9.8=frac{1}{2} times 98 times frac{1}{2} times t^{2} )

( Rightarrow 1=frac{1}{4} times t^{2} )

( Rightarrow 4=t^{2} )

( therefore t=2 sec )