Question

A boy with a mass of 25 kg is sitting in a red wagon of mass 8.5 kg which is at rest. His friend begins pulling him forward, accelerating him with a constant force for 2.35 s to a speed of 1.8 m/s. Calculate the force with which the wagon was being pulled.

4.2 N

25.7 N

19.1 N

6.5 N

Answer 1

So, the force that given when the wagon was being pulled is approximately 19.1 N (C).

Introduction

Hi ! For intermesso, this question will adopt a lot about the relationship of impulse to change in momentum. Impulse is the total force applied in a certain time interval. Impulses can cause a change of momentum, because momentum itself is a mass that is affected by the velocity of an object. We know that velocity is a vector quantity easy to change its direction. The relationship between impulse and change in momentum is formulated by :

`\sf{I = \Delta p}`

`\sf{F \cdot \Delta t = (m \cdot v') - (m \cdot v)}`

`\boxed{\sf{\bold{F \cdot \Delta t = m (v' -v)}}}`

With the following condition :

• I = impulse that given (N.s)
• 
  `\sf{\Delta p}` = change of momentum (kg.m/s)
• F = force that given (N)
• m = mass of the object (kg)
• v = initial velocity (m/s)
• v' = final velocity (m/s)
• 
  `\sf{\Delta t}` = interval of the time (s)

Problem Solving

We know that :

• m = mass of the object = 25 kg
• v = initial velocity = 0 m/s
• v' = final velocity = 1.8 m/s
• 
  `\sf{\Delta t}` = interval of the time = 2.35 s

What was asked :

• F = force that given = ... N

Step by step :

`\sf{F \cdot \Delta t = m (v' -v)}`

`\sf{F \cdot 2.35 = 25 (1.8 - 0)}`

`\sf{F = (25 (1.8))/(2.35)}`

`\boxed{\sf{F = 19.15 \: N \approx 19.1 \: N}}`

Conclusion

So, the force that given when the wagon was being pulled is approximately 19.1 N (C).