Question

mid year practice

1. scientists make models to help explain things that are different or impossible to observe directly. scientists have revised the model of the atom numerous times. the image below shows several scientific models of the atom.

nos: models
why would scientists most likely revise a scientific model?
advances in science can show how older models are flawed.
newer models tend to look more appealing than older models.
older models tend to be less informative than newer models.
old technology did not allow scientists to accurately measure.

1. a student is measuring the force required to move an object. which of

the forces shown in the diagram is a noncontact force? forces
force of friction\tforce of student’s pull
force of gravity\tforce of the table

1. two forces are applied on a soccer ball. which explains why the ball accelerates? balanced/unbalanced forces

a net force applied to the ball is 0 n.\tthe ball resists one force but not the other.
newton’s second law does not apply to round objects.\tthe two forces are unbalanced.

Explanation:

Question 9

Scientists revise scientific models mainly because new scientific advancements (like new experimental methods, discoveries) reveal flaws in older models. The option about models looking more appealing is incorrect as scientific models are for explanation, not aesthetics. Older models being less informative is not the primary reason for revision; it's about flaws shown by new science. Old technology affecting measurement is about data collection, not model revision directly. So the correct reason is "Advances in science can show how older models are flawed."

Non - contact forces are forces that act without physical contact. Friction (between object and surface), student's pull (direct contact), and force of the table (normal force, contact) are contact forces. Gravity acts on the object without touching it, so it's a non - contact force.

According to Newton's second law, an object accelerates when there is a net non - zero force acting on it, which happens when forces are unbalanced. If net force is 0 N, the object either remains at rest or moves at constant velocity (no acceleration). The idea that the ball resists one force but not the other is incorrect, and Newton's second law applies to all objects regardless of shape. So the correct explanation is "The two forces are unbalanced."

Answer:

Advances in science can show how older models are flawed.

Question 10