I think some of the posts on here fail to account for time to spool a fan engine while the aircraft is moving. The 777 is going to need 8 or more seconds to spool a engine. If the reverser is unlocked even longer. At 100 knots you are traveling almost 170 feet per second. You will need almost 1400 feet of runway before you reach Go Around power. You now need to accelerate to takeoff speed before getting airborne. call it 3000 feet and you might be close to clear a very short obstacle. Again if the reversers are unlocked this distance will be longer. Just a guess but I bet most airliners can stop from 100 knots in 1500 feet or less on a dry runway with maximum braking.