Question

when a swimmer pushes water backward with their hands (action), the water pushes the swimmer forward (reaction). this is an example of:
a) newtons first law of motion
b) newtons second law of motion
c) newtons third law of motion
d) the law of universal gravitation
a force of 30 n is applied to an object, causing it to accelerate at 6 m/s2. what is the mass of the object?
a) 0.2 kg
b) 5 kg
c) 36 kg
d) 180 kg

Explanation:

First Question (Swimmer and Newton's Law)

Newton's Third Law of Motion states that for every action, there is an equal and opposite reaction. The swimmer pushing water backward (action) and water pushing the swimmer forward (reaction) fits this law. Newton's First Law is about inertia, Second about \( F = ma \), and Universal Gravitation is about gravity between masses. So the correct option is related to the Third Law.

Step1: Recall Newton's Second Law

Newton's Second Law is \( F = ma \), where \( F \) is force, \( m \) is mass, and \( a \) is acceleration. We need to solve for \( m \), so rearrange the formula to \( m=\frac{F}{a} \).

Step2: Substitute the values

Given \( F = 30\space N \) and \( a = 6\space m/s^2 \). Substitute into the formula: \( m=\frac{30}{6}=5\space kg \).

Answer:

c) Newton's Third Law of Motion

Second Question (Force, Acceleration, Mass)