Which one of the following statements is true concerning the motion of an ideal projectile launched at an angle of 45° to the horizontal?
Correct answer: E. The vertical speed decreases on the way up and increases on the way down.
- A. The acceleration vector points opposite to the velocity vector on the way up and in the same direction as the velocity vector on the way down.
- B. The speed at the top of the trajectory is zero.
- C. The object's total speed remains constant during the entire flight.
- D. The horizontal speed decreases on the way up and also decreases on the way down.
- E. The vertical speed decreases on the way up and increases on the way down.
Explanation
The only external force acting on the object is the gravitational force vertically downwards. Thus the acceleration of the projectile is g downwards always. Thus there is no change in the speed of the object in the horizontal direction. The speed of an object in the vertical direction at the top of the trajectory is zero. However, the net speed at the point is equal to the constant horizontal component. Due to downward constant acceleration, the vertical speed decreases way up, becomes zero, and then increases way down. Thus option E is correct.
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: