Question

Trevor, imprisoned in a cell, wishes to get a message to his friend, Franklin who is loitering outside a wall surrounding his prison. Trevor has wrapped his message round a stone, and intends to throw it from his prison cell window, over the wall, to land where Franklin can retrieve it. Trevor can throw the stone at 16 m/s. The cell window from which he can throw the stone is 6 m above the level ground outside the prison. The wall rises 10 m above the ground outside the prison, and is at a horizontal distance of 20 m from Trevor’s cell window. The stone has mass 0.2 kg.

a) Suppose that Trevor throws the stone at an angle of 2π / 9 radians (40 degrees) above the horizontal. Describe whether the stone will clear the wall, neglecting air resistance.

b) Analyze what range of launch angles will enable Trevor to get the stone over the wall, if air resistance can be neglected?

c) Trevor wants to throw the stone so that it lands as far as possible from the wall, to reduce the chances of Franklin being detected as he searches for it. Describe what launch angle should he choose (still neglecting air resistance and stone must clear the wall)? For this launch angle, analyze how far beyond the wall will the stone land?

Answer 1