A firefighter jumps horizontally from a burning building with an initial speed of 1.5 m/s. At what time is the angle between his velocity and acceleration vectors the greatest?
Correct answer: A. The instant he jumps.
- A. The instant he jumps.
- B. When he reaches terminal velocity
- C. Halfway through his fall
- D. Right before he lands on the ground
Explanation
When the firefighter jumps horizontally from the building, his initial velocity is purely horizontal (since no vertical component is mentioned).At the moment of jumping, the acceleration due to gravity acts vertically downward. The angle between the horizontal velocity and vertical acceleration vectors is 90 degrees, making it the greatest angle between these vectors.As the firefighter falls, the angle between the velocity and acceleration vectors decreases until he reaches the maximum speed vertically downward when the angle is 0 degrees, aligning with the acceleration due to gravity.
Last updated
About Force and Motion
Displacement, velocity and acceleration describe motion, including the horizontal and vertical components of projectile motion. The chapter connects these quantities with Newton's laws, momentum and impulse, then applies conservation of momentum to collisions, distinguishing elastic collisions from inelastic ones.
Practise Force and Motion
1,416 free Force and Motion MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Physics questions like this
Physics is on 13 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
Related questions
(1, 1, 1) . (2, 2, 2)
1st law of motion gives the definition of:
2nd law of motion measures which quantity?
7.0 kg bowling ball experience a net force of 5.0N. What will be its acceleration?
A 0.2 kg rubber ball is dropped from the window of a building. It strikes the sidewalk below at 30m/s and rebounds up at 20m/s. The impulse on the ball during the collision is: