Newton's problem solving and logic questions

Question 1

While ice skating, Chris (75 kg) and Jade (65 kg) come together and then push off each other’s palms so that they move backwards, away from each other. Which of the following best describes the forces involved? State a reason why.

A. Chris exerts a larger force on Jade because he has a larger mass
B. Jade exerts a larger force on Chris because he has a larger mass
C. Neither exerts any force because the forces cancel out
D. They both exert the same amount of force on each other

Answer 1

D

The answer is D. This is because according to Newton’s third law of motion, in every force in nature, there is always an equal and opposite force. Thus, they both exert the same amount of force on each other. However, there is a difference in the accelerations because of the differences in mass.

Question 2

What is normal force?

Answer 2

Normal force is defined as the force that a surface exerts on the object. The normal force is NORMALLY EQUAL to the FORCE DUE TO GRAVITY (WEIGHT)

It is normally the opposite of the force of gravity (demonstrated on a free body diagram)

Question 3

Does an object with a big mass have a higher or lower acceleration than a small mass?

Answer 3

An object with a big mass has low acceleration but a small mass has high acceleration

Question 4

Why does a change in direction mean acceleration?

Since acceleration = final velocity - initial velocity / change in time,

Answer 4

When an object changes directions, the velocity also changes directions . (Because it is a vector quantity) Changing directions in velocity would ultimately be a sign of acceleration, which by definition means the rate at which an object changes it’s velocity

Question 5

Explain why the two forces in an action–reaction force pair have to act on two different objects. Predict the result if the two forces acted on the same object in opposite directions. Explain your answer.

Answer 5

The action and reaction forces MUST occur on different objects. If it happened on the same object, then the action and reaction force would cancel out, creating zero net force. 0 netforce would imply that the object is stationary which doesn’t make sense, especially in examples where a bat hits a ball and the ball goes flying while the bat moves opposite in direction.

Question 6

Use the concept of inertia to explain the relationship between the mass and acceleration of two objects of different mass acted on by the same force.

Answer 6

Different mass but same force means different accelerations.

Question 7

Angus inadvertently drops an egg while baking a cake,
and the egg falls vertically towards the ground. Which
one of the following statements correctly describes
how the egg falls?

A The egg’s acceleration increases.
B The egg’s acceleration is constant
C The egg’s velocity is constant
D The egg’s acceleration decreases.

Answer 7

B, the egg’s acceleration is constant