Linear momentum – problems and solutions

1. An object travels at a constant 10 m/s. Calculate the linear momentum of the object.

Known :

Mass (m) = 1 kg

Velocity (v) = 10 m/s

Wanted : linear momentum (p)

Solution :

Formula of the linear momentum :

p = m v

p = linear momentum, m = mass, v = velocity

The linear momentum :

p = m v = (1)(10) = 10 kg m/s²

2. A 2-kg block and a 4-kg blocks moves at a constant 20 m/s. What is the linear momentum of the blocks.

Known :

Mass of block A (m_A) = 2 kg

Mass of block B (m_B) = 4 kg

Velocity of block A (v_A) = 20 m/s

Velocity of block B (v_B) = 20 m/s

Wanted : Linear momentum of block A (p_A) and linear momentum of block B (p_B)

Solution :

Linear momentum of block A :

p_A = m_A v_A = (2)(20) = 40 kg m/s

Linear momentum of block B :

p_B = m_B v_B = (4)(20) = 80 kg m/s

3. A 2-kg block moves at a constant 2 m/s and a 2-kg block moves at a constant 4 m/s. Determine the linear momentum of the blocks.

Known :

Mass of block A (m_A) = 2 kg

Mass of block B (m_B) = 2 kg

Velocity of block A (v_A) = 2 m/s

Velocity of block B (v_B) = 4 m/s

Wanted : the linear momentum of blocks

Solution :

Linear momentum of block A :

p_A = m_A v_A = (2)(2) = 4 kg m/s

Linear momentum of block B :

p_B = m_B v_B = (2)(4) = 8 kg m/s

4. A 5-kg object at rest. What is the linear momentum of the momentum.

Known :

Mass (m) = 5 kg

Object’s velocity (v) = 0

Wanted : the linear momentum (p)

Solution :

p = m v = (5)(0) = 0

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