1. Mass of the hockey ball, m= 200 g = 0.2 kg Hockey ball travels with velocity, v₁= 10 m/s Initial momentum = mv₁ Hockey ball travels in the opposite direction with velocity, v₂= -5 m/s Final momentum = mv₂ Change in momentum = mv₁- mv₂= 0.2 [10 - (-5)] = 0.2 (15) = 3 kg m s⁻¹ Hence, the change in momRead more

    Mass of the hockey ball, m= 200 g = 0.2 kg
    Hockey ball travels with velocity, v₁= 10 m/s
    Initial momentum = mv₁
    Hockey ball travels in the opposite direction with velocity, v₂= -5 m/s
    Final momentum = mv₂
    Change in momentum = mv₁- mv₂= 0.2 [10 – (-5)] = 0.2 (15) = 3 kg m s⁻¹
    Hence, the change in momentum of the hockey ball is 3 kg m s⁻¹.

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-9/

    See less
    • 0
  2. The truck has a large mass. Therefore, the static friction between the truck and the road is also very high. To move the car, one has to apply a force more than the static friction. Therefore, when someone pushes the truck and the truck does not move, then it can be said that the applied force in onRead more

    The truck has a large mass. Therefore, the static friction between the truck and
    the road is also very high. To move the car, one has to apply a force more than
    the static friction. Therefore, when someone pushes the truck and the truck does
    not move, then it can be said that the applied force in one direction is cancelled
    out by the frictional force of equal amount acting in the opposite direction.
    Therefore, the student is right in justifying that the two opposite and equal cancel
    each other.

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-9/

    See less
    • 0
  3. Mass of one of the objects, m₁ = 1.5 kg Mass of the other object, m₂ = 1.5 kg Velocity of m1 before collision, v₁ = 2.5 m/s Velocity of m₂, moving in opposite direction before collision, v₂ = -2.5 m/s (Negative sign arises because mass m₂ is moving in an opposite direction) After collision, the twoRead more

    Mass of one of the objects, m₁ = 1.5 kg
    Mass of the other object, m₂ = 1.5 kg
    Velocity of m1 before collision, v₁ = 2.5 m/s
    Velocity of m₂, moving in opposite direction before collision, v₂ = -2.5 m/s
    (Negative sign arises because mass m₂ is moving in an opposite direction)
    After collision, the two objects stick together.
    Total mass of the combined object = m₁ + m₂
    Velocity of the combined object = v
    According to the law of conservation of momentum:
    Total momentum before collision = Total momentum after collision
    m₁ + v₁ + m₂ v₂= (m₁ + m₂) v
    1.5(2.5) + 1.5 (-2.5) = (1.5 + 1.5) v
    3.75 – 3.75 = 3 v
    v = 0
    Hence, the velocity of the combined object after collision is 0 m/s.

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-9/

    See less
    • 0
  4. A force of 200 N is applied in the forward direction. Thus, from Newton's third law of motion, an equal amount of force will act in the opposite direction. This opposite force is the fictional force exerted on the cabinet. Hence, a frictional force of 200 N is exerted on the cabinet. For more answerRead more

    A force of 200 N is applied in the forward direction. Thus, from Newton’s third
    law of motion, an equal amount of force will act in the opposite direction. This
    opposite force is the fictional force exerted on the cabinet. Hence, a frictional
    force of 200 N is exerted on the cabinet.

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-9/

    See less
    • 1
  5. (d) mv Mass of the object = m Velocity = v Momentum = Mass × Velocity Momentum = mv

    (d) mv
    Mass of the object = m
    Velocity = v
    Momentum = Mass × Velocity
    Momentum = mv

    See less
    • 0