Lesson_3.1_Homework_Solution

Lesson_3.1_Homework_Solution - Lesson 3.1 Homework...

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Lesson 3.1 Homework Solutions 1. Vector A = 2 i – 3 j and vector B = -4 i + 6 j . Find A B and the angle between the two vectors. A = 2 i – 3 j , B = -4 i + 6 j A B = -8 – 18 = -26 2 2 2 2 2 3 3.6 4 6 7.2 26 cos 1 3.6 7.2 A B A B A B θ = + = = + = - = = = - × θ = cos -1 = 180 o 2. A force F = 3 N i – 5 N j produces a displacement on a particle given by s = 5 m i – 2 m j . Find the work done by the force. F = 3 N i – 5 N j , s = 5 m i – 2 m j . W = F s = 15 + 10 = 25 J 3. What is the work done to raise a 50-kg box to a height of 3.0 m? The force needed to raise the box is its weight = 50 × 9.8 = 490 N W = F y = 490 N × 3.0 m = 1470 J 4. A tractor exerts a constant force of 4.5 × 10 4 N in moving a load horizontally a distance of 150 m. (i) What is the work done? (ii) If the tractor does this work in 45 s, what is the power developed by its engine? (i)
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Lesson_3.1_Homework_Solution - Lesson 3.1 Homework...

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