Question

1. choose the best answer.

the total amount of ground an object covers during its journey is _.
speed
velocity
distance
acceleration

1. choose the best answer.

exactly how fast something is moving every second is uncertain because _ will o
direction
the range
trajectory
speed

Explanation:

• Question 18:
• Speed: It is the rate at which an object covers distance (\(speed=\frac{distance}{time}\)), not the total amount of ground covered.
• Velocity: It is a vector quantity (\(velocity = \frac{displacement}{time}\)), which involves both magnitude and direction, not just the total ground covered.
• Distance: It is a scalar quantity that refers to "how much ground an object has covered" during its motion.
• Acceleration: It is the rate of change of velocity (\(a=\frac{\Delta v}{\Delta t}\)), not related to the total ground covered.
• Question 19:
• Direction: When we talk about exactly how fast something is moving every second (i.e., instantaneous speed or velocity), if we consider velocity (a vector), direction can change. For example, in circular motion, the speed (magnitude of velocity) can be constant, but the direction of velocity is changing every second.
• The range: This term is not relevant in the context of how - fast - something - is - moving - every - second in basic kinematics.
• Trajectory: While trajectory is related to the path of motion, it is not the direct reason for the uncertainty in "how fast something is moving every second" in the sense of vector quantity (velocity).
• Speed: Speed is a scalar. If we just consider speed (magnitude), it doesn't have the uncertainty due to direction change (as velocity does).

Answer:

1. C. distance
2. A. direction