Question

8 A boy intends to move an m-kg crate across the floor by applying a constant force P newtons on it.The coeficient of friction between the floor and the crate is $\mu$. Which of these is the best option for his task?
Pull the crate with P applied horizontally
Push the crate with P inclined at an angle above the horizontal
Pull the crate with P inclined at an angle above the horizontal
Pull the crate with P inclined an angle below the horizontal

9 A boat propelled so as to travel with a speed of 0.50m/s in still water, moves directly (in a straight line) across a river that is 60m wide. The river flows with a speed of 0.30m/s. How long in seconds does it take the boat to cross the river?
36
120
150
200