Practice important
Projectile Components
MCQ questions and answers.
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MCQ Questions
1. A projectile is launched with speed 20 m/s at an angle of 30° above the horizontal. What is its horizontal component of initial velocity?
A.
10 m/s
B.
17.3 m/s
C.
20 m/s
D.
5 m/s
Correct Answer:
17.3 m/s
Explanation:
The horizontal component is u cos θ = 20 cos 30° = 20 × 0.866 ≈ 17.3 m/s.
2. A projectile is launched with speed 20 m/s at an angle of 30° above the horizontal. What is its vertical component of initial velocity?
A.
17.3 m/s
B.
20 m/s
C.
10 m/s
D.
5 m/s
Correct Answer:
10 m/s
Explanation:
The vertical component is u sin θ = 20 sin 30° = 20 × 0.5 = 10 m/s.
3. In projectile motion, which component of velocity remains constant when air resistance is neglected?
A.
Vertical component
B.
Horizontal component
C.
Both components increase equally
D.
Both components become zero
Correct Answer:
Horizontal component
Explanation:
There is no horizontal acceleration when air resistance is neglected, so the horizontal component of velocity remains constant.
4. What is the horizontal component of acceleration for a projectile moving under gravity alone?
A.
9.8 m/s²
B.
Zero
C.
4.9 m/s²
D.
19.6 m/s²
Correct Answer:
Zero
Explanation:
Gravity acts vertically downward, so it produces no horizontal acceleration.
5. What is the vertical component of acceleration of a projectile near Earth, taking upward as positive?
A.
Zero
B.
+9.8 m/s²
C.
-9.8 m/s²
D.
+4.9 m/s²
Correct Answer:
-9.8 m/s²
Explanation:
Gravity acts downward. Therefore, when upward is taken as positive, the vertical acceleration is -9.8 m/s².
6. A ball is projected horizontally from a height. What is its initial vertical component of velocity?
A.
Equal to its horizontal velocity
B.
Zero
C.
9.8 m/s
D.
Maximum
Correct Answer:
Zero
Explanation:
A horizontal projection has no initial motion in the vertical direction, so its initial vertical velocity component is zero.
7. At the highest point of a projectile's path, what is the vertical component of its velocity?
A.
Maximum
B.
Equal to the horizontal component
C.
Zero
D.
Equal to gravitational acceleration
Correct Answer:
Zero
Explanation:
The projectile stops moving upward momentarily at the highest point, so its vertical velocity component is zero.
8. A projectile is launched with an initial velocity of 10 m/s at an angle of 60° above the horizontal. Which expression gives its vertical component of initial velocity?
A.
10 cos 60°
B.
10 sin 60°
C.
10 tan 60°
D.
10 divided by sin 60°
Correct Answer:
10 sin 60°
Explanation:
The vertical component of an initial velocity is found using u sin θ, so it is 10 sin 60°.
9. A projectile has horizontal and vertical velocity components of 6 m/s and 8 m/s, respectively. What is its speed at that instant?
A.
2 m/s
B.
10 m/s
C.
14 m/s
D.
48 m/s
Correct Answer:
10 m/s
Explanation:
The speed is the resultant of the perpendicular components: v = √(6² + 8²) = √100 = 10 m/s.
10. A projectile is launched at an angle of 90° to the horizontal. What is its initial horizontal component of velocity?
A.
Equal to its initial speed
B.
Half its initial speed
C.
Zero
D.
Twice its initial speed
Correct Answer:
Zero
Explanation:
The horizontal component is u cos 90°, and cos 90° = 0. Therefore, the initial horizontal component is zero.