What would be Kelly's weight in newtons if her mass is 70 kilograms?
A. [tex]$70 \times g$[/tex]
B. 70
[tex]$g$[/tex]
C. 70
[tex]$g^2$[/tex]
D. [tex]$70 \times g^2$[/tex]
E. 70
Answer (1)
Weight is calculated as mass times the acceleration due to gravity.
Given Kelly's mass is 70 kg, her weight is 70 × g newtons.
The correct expression for Kelly's weight is 70 × g .
Therefore, Kelly's weight in newtons is 70 × g .
Explanation
Understanding the Problem We are given Kelly's mass, which is 70 kilograms, and we need to find her weight in newtons. Weight is the force of gravity acting on an object and is calculated using the formula: weight = mass × acceleration due to gravity. The acceleration due to gravity is denoted by 'g'.
Recalling the Formula The formula to calculate weight (W) is: W = m × g where:
W is the weight in newtons (N)
m is the mass in kilograms (kg)
g is the acceleration due to gravity (approximately 9.8 m/s²)
Substituting the Given Mass We are given that Kelly's mass (m) is 70 kg. Substituting this into the formula, we get: W = 70 × g This means Kelly's weight in newtons is 70 times the acceleration due to gravity.
Finding the Correct Option The correct answer is therefore: 70 × g
Examples
Understanding weight is crucial in many real-world scenarios. For example, when designing bridges or buildings, engineers need to calculate the weight of materials to ensure structural integrity. Similarly, in sports, understanding weight and its effects on motion is important for optimizing performance. For instance, a weightlifter needs to know how much force they need to exert to lift a certain weight, and a cyclist needs to consider the weight of their bike when climbing a hill. This concept is fundamental in physics and engineering.
