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 :

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

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

$\sf{F = \frac{25 (1.8)}{2.35}}$

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

Conclusion

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