Unit 5 Newton's Law of Motion CP Physics Review

What happens to an object when the net force acting on it is zero?

• a. It moves with constant velocity.

• b. It accelerates.

• c. Its mass increases.

• d. Its speed decreases gradually.

Answer explanation

When the net force on an object is zero, it means there is no unbalanced force acting on it. According to Newton's first law, the object will either remain at rest or move with constant velocity, making option a the correct choice.

Tags

NGSS.HS-PS2-1

According to Newton's second law of motion, the acceleration of an object is directly proportional to the _____ and inversely proportional to its _____.

• a. net force, mass

• b. velocity, volume

• c. mass, net force

• d. gravity, area

Answer explanation

According to Newton's second law, acceleration (a) is directly proportional to the net force (F) acting on an object and inversely proportional to its mass (m). Thus, the correct answer is a. net force, mass.

Tags

NGSS.HS-PS2-1

An object with a mass of 20 kg is pushed with a force of 40 N. What is the acceleration of the object?

• a. 2 m/s²

• b. 8 m/s²

• c. 20 m/s²

• d. 0.5 m/s²

Answer explanation

Using Newton's second law, F = ma, we can find acceleration (a) by rearranging the formula: a = F/m. Here, F = 40 N and m = 20 kg. Thus, a = 40 N / 20 kg = 2 m/s². Therefore, the correct answer is a. 2 m/s².

Tags

NGSS.HS-PS2-1

Which vector diagram accurately depicts an object in motion at constant velocity on a flat surface?

• 1

• 2

• 3

Answer explanation

Vector diagram 3 accurately shows an object moving at constant velocity on a flat surface, indicated by a straight arrow with no change in direction or speed, reflecting uniform motion.

Which vector diagram correctly illustrates a cart accelerating to the left?

• 1

• 2

• 3

Answer explanation

The correct vector diagram is 2, as it shows an arrow pointing to the left, indicating the direction of acceleration for the cart. Diagrams 1 and 3 do not represent leftward acceleration.

Tags

NGSS.HS-PS2-1

A car moving in a circular path at uniform speed has _____.

• a. its velocity constant.

• b. a net force acting towards the center of the circle.

• c. no acceleration acting on it.

Answer explanation

A car moving in a circular path at uniform speed experiences a net force directed towards the center of the circle, known as centripetal force. This force is necessary for maintaining circular motion.

Tags

NGSS.HS-PS2-1

What is the force required to maintain the velocity of an object moving in space, assuming no external forces?

• a. Equal to the force initially applied to set it in motion.

• b. Zero, because objects in motion remain in motion unless acted upon by an external force.

• c. Twice the initial force to overcome space resistance.

• d. It gradually increases as the object moves further into space.

Answer explanation

The correct answer is b. Zero, because according to Newton's first law, an object in motion will remain in motion at a constant velocity unless acted upon by an external force. In space, with no external forces, no additional force is needed.

Tags

NGSS.HS-PS2-1

What is the minimum resultant possible when adding a 3-N force to a 5-N force in the opposite direction?

• a. 2 N

• b. 3 N

• c. 5 N

• d. 8 N

Answer explanation

When adding a 3-N force to a 5-N force in opposite directions, you subtract the smaller force from the larger one: 5 N - 3 N = 2 N. Thus, the minimum resultant possible is 2 N.

Tags

NGSS.HS-PS2-1

Newton's third law states that for every action, there is an equal and opposite _____.

• a. reaction.

• b. acceleration.

• c. force.

Answer explanation

Newton's third law states that for every action, there is an equal and opposite reaction. Therefore, the correct answer is 'reaction', as it directly completes the law's statement.

Tags

NGSS.MS-PS2-1

Newton's third law states that for every action there is

• an equal and opposite reaction.

• a similar action in the same direction.

• no significant effect.

• a reaction that cancels the action.

Answer explanation

Newton's third law states that for every action, there is an equal and opposite reaction. This means that forces always occur in pairs, where one force is matched by another in the opposite direction.