Which three options are true about motion in a straight line.
A. A particle which moves at an increasing velocity has a constant acceleration.
B. If two particles always have the same velocity as each other, their separation does not change.
C. A particle which has zero acceleration moves with constant velocity or is stationary.
D. A particle with negative position must have had a negative acceleration in the past.
E. The acceleration of any subject is 9.8m s^-2
F. A particle which moves with a constant acceleration also has a constant velocity.
G. An object which is dropped and falls only under gravity accelerates downwards at approximately 9.8m s^-2
H. Velocity is the magnitude of the speed.
I think A, B and G. Can anyone help?
To determine which options are true about motion in a straight line, let's analyze each statement:
A. A particle which moves at an increasing velocity has a constant acceleration.
This statement is false. If the velocity of a particle is increasing, it means it has a non-zero acceleration.
B. If two particles always have the same velocity as each other, their separation does not change.
This statement is true. If two particles have the same velocity, it means they are moving together and their separation remains constant.
C. A particle which has zero acceleration moves with constant velocity or is stationary.
This statement is true. Zero acceleration means no change in velocity, so the particle either moves with a constant velocity or remains stationary.
D. A particle with negative position must have had a negative acceleration in the past.
This statement is false. Negative position does not necessarily indicate negative acceleration. It only signifies that the particle is positioned in the negative direction relative to a reference point.
E. The acceleration of any subject is 9.8 m s^-2.
This statement is false. The value of 9.8 m/s^2 represents the acceleration due to gravity near the surface of the Earth, but it is not the universal acceleration for all objects.
F. A particle which moves with a constant acceleration also has a constant velocity.
This statement is false. A particle moving with a constant acceleration does not have a constant velocity. The velocity of an object undergoing constant acceleration changes at a uniform rate.
G. An object dropped and falls only under gravity accelerates downwards at approximately 9.8 m s^-2.
This statement is true. When an object is dropped and falls freely under the influence of gravity, it accelerates downward at approximately 9.8 m/s^2. This is the acceleration due to gravity near the surface of the Earth.
H. Velocity is the magnitude of the speed.
This statement is true. Velocity is a vector quantity that includes both magnitude (speed) and direction. The magnitude of the velocity vector is the speed.
Based on the analysis:
The correct options that are true about motion in a straight line are:
B. If two particles always have the same velocity as each other, their separation does not change.
C. A particle which has zero acceleration moves with constant velocity or is stationary.
G. An object which is dropped and falls only under gravity accelerates downwards at approximately 9.8 m/s^2.