Advertisements
Advertisements
Question
An object of mass 1 kg travelling in a straight line with a velocity of 10 ms−1 collides with, and sticks to, a stationary wooden block of mass 5 kg. Then they both move off together in the same straight line. Calculate the total momentum just before the impact and just after the impact. Also, calculate the velocity of the combined object.
Advertisements
Solution
Mass of object, m1 = 1 kg
The velocity of an object before the collision, u1 = 10 m s-1
Mass of wooden block, m2 = 5 kg
The velocity of the wooden block before the collision, u2= 0
(i) ∴ Total momentum before the impact = m1 u1 + m2 u2
= 1 × 10 + 5 × 0
= 10 kg ms-1
According to the law of conservation of momentum (as no net external force acts on the system),
Total momentum after the impact = Total momentum before the impact = 10 kg ms-1
(ii) Mass of combined object, M = mass of object + mass of block
= 1 + 5
= 6 kg
Let V = Velocity of the combined object after collision
∴ Momentum of combined object = MV
= (6V) kg ms-1
Now, the momentum of the combined object Total momentum after the impact
i.e., 6V = 10
or V = `10/6`
= 1.67 ms-1
APPEARS IN
RELATED QUESTIONS
Two objects, each of mass 1.5 kg are moving in the same straight line but in opposite directions. The velocity of each object is 2.5 m s−1 before the collision during which they stick together. What will be the velocity of the combined object after collision?
Akhtar, Kiran and Rahul were riding in a motorcar that was moving with a high velocity on an expressway when an insect hit the windshield and got stuck on the windscreen. Akhtar and Kiran started pondering over the situation. Kiran suggested that the insect suffered a greater change in momentum as compared to the change in momentum of the motorcar (because the change in the velocity of the insect was much more than that of the motorcar). Akhtar said that since the motorcar was moving with a larger velocity, it exerted a larger force on the insect. And as a result the insect died. Rahul while putting an entirely new explanation said that both the motorcar and the insect experienced the same force and a change in their momentum. Comment on these suggestions.
A stream of water flowing horizontally with a speed of 15 m s–1 gushes out of a tube of cross-sectional area 10–2 m2, and hits a vertical wall nearby. What is the force exerted on the wall by the impact of water, assuming it does not rebound?
What is the total momentum of the bullet and the gun before firing ?
Explain the meaning of the following equation : .
p = m x v
where symbols have their usual meanings.
A man throws a ball weighing 500 g vertically upwards with a speed of 10 m/s.
- What will be its initial momentum ?
- What would be its momentum at the highest point of its flight ?
Name the principle on which a rocket works.
A body of mass 2 kg is at rest. What should be the magnitude of force which will make the body move with a speed of 30 m/s at the end of 1 s ?
State the law of conservation of momentum.
An unloaded truck weighing 2000 kg has a maximum acceleration of 0.5 m/s2. What is the maximum acceleration when it is carrying a load of 2000 kg ?
