For motion in two or three dimensions, what is the angle between velocity and acceleration vectors?
A.
0°
B.
180°
C.
Between 0° and 180°
D.
90°
Answer: Option C
Explanation:
For motion in one dimension, the velocity and acceleration are always along the same line either in the same direction or in opposite direction. For motion in two or three dimensions, the angle between velocity and acceleration vectors may have any value between 0° and 180°.
An object thrown from an aeroplane is an example for?
A.
Projectile motion
B.
Resolution of forces
C.
Composition of vectors
D.
Addition of vectors
Answer: Option A
Explanation:
A projectile is a name given to anybody which once thrown into space with some initial velocity, moves thereafter under the influence of gravity alone without being propelled by an engine or fuel. The path followed by a projectile is called its trajectory
A ball is dropped downward from the roof of a building and simultaneously another ball is thrown in a horizontal direction, when will the balls reach the ground?
A.
Same time and same place
B.
The first ball will reach later than the second ball
C.
The second ball will reach later than the second ball
D.
Same time but different places
Answer: Option D
Explanation:
Both the balls will reach the ground at the same time but at different places. The vertical motion is not affected by the horizontal motion. This is called the principle of physical independence.
. A body is projected horizontally from the top of a cliff with a velocity of 9.8m/s. What time elapses before horizontal and vertical velocities become equal? Take g = 9.8m/s2?
A.
9.8s
B.
0s
C.
10s
D.
1s
Answer: Option D
Explanation:
Horizontal velocity at any instant, vx = u = 9.8m/s
Vertical velocity at any instant, vy = 0 + gt = 9.8t
