Discussion
An airplane requires a longer ground roll to lift-off on hot summer days because
Answer: A
The reason is that the thrust is directly proportional to free-stream density.
Hot air is less dense. An engine's thrust falls with air density (in the simple model it is taken as directly proportional to it), so on a hot day the aircraft accelerates more slowly. The thinner air also raises the speed needed to make lift equal weight, so the aircraft must reach a higher speed with less thrust, and the ground roll lengthens.
Thrust does not depend on the aircraft's weight. The lift-off distance is inversely related to density (it grows as density falls), not directly proportional to it. Runway friction is not what changes on a hot day; the density of the air is.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development