Asked by silverback
                12 kg wagon is being pulled at an angle of 38o above horizontal. What force is applied to the wagon if it accelerates from rest to a speed of 2.2 m/s over a distance of 3.4 m? Is this question a typo? Am I supposed to solve for force or work?
            
            
        Answers
                    Answered by
            silverback
            
    I need help
    
                    Answered by
            Damon
            
    F cos 38 = m a
easy way is for constant acceleration
v average = (Vi+Vf)/2
so
v average = (0 + 2.2)/2 = 1.1 m/s
so time = t = 3.4/1.1 = 3.09 s
a = change in v / time
= 2.2 / 3.09
= .712 m/s^2
so
F cos 38 = 12 * .712
F = 10.8 Newtons
    
easy way is for constant acceleration
v average = (Vi+Vf)/2
so
v average = (0 + 2.2)/2 = 1.1 m/s
so time = t = 3.4/1.1 = 3.09 s
a = change in v / time
= 2.2 / 3.09
= .712 m/s^2
so
F cos 38 = 12 * .712
F = 10.8 Newtons
                    Answered by
            silverback
            
    This is from one of your previous answers. You can do it with work if you wish or you can do it with F = m a 
with work
work done = Force in direction of motion * distance
Force in direction of motion = F cos 38
= .788 F
work done = .788 F * 3.4 meters
= 2.68 F Joules
that is the increase in kinetic energy
(1/2) m v^2 = .5*12 * 2.2^2
= 29 Joules
so
2.68 F = 29
F = 10.8 Newtons
Why did you use kinetic energy is equal to work?
    
with work
work done = Force in direction of motion * distance
Force in direction of motion = F cos 38
= .788 F
work done = .788 F * 3.4 meters
= 2.68 F Joules
that is the increase in kinetic energy
(1/2) m v^2 = .5*12 * 2.2^2
= 29 Joules
so
2.68 F = 29
F = 10.8 Newtons
Why did you use kinetic energy is equal to work?
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