How much momentum will a dumb-bell of mass 10 kg transfer to the floor if it falls from a height of 80 cm? Take its downward acceleration to be 10 m s–2.
Solution and Explanation
m= 10 kg,u= 0 (Since the dumb-bell falls from rest) Distance covered, s= 80cm = 0.8m a= 10 ms-2
From equation of motion, v2=u2+ 2as
v2= 0 + 2 × 10 × 0.8
= 16 = v = \(\sqrt{16}\) = 4ms-1
Momentum of dumb-bell just before it touches the floor
p = mv = 10 × 4 = 40 kg-ms-1
When the dumb-bell touches the floor, its velocity becomes zero. Thus, the total momentum of the dumb-bell is transferred to the floor. Hence, the momentum transferred to floor = 40 kg-ms-1.
Top Questions on Newton’s Second Law Of Motion
- A mass of 200 gm has initial velocity \(v_i = 2\hat{i}+3\hat{j}\) and final velocity \(v_f=-2\hat{i}-3\hat{j}\) find magnitude of change in momentum
- JIPMER MBBS - 2018
- Physics
- Newton’s Second Law Of Motion
- A stone of 1 kg is thrown with a velocity of 20 m s–1 across the frozen surface of a lake and comes to rest after traveling a distance of 50 m. What is the force of friction between the stone and the ice?
- CBSE Class IX
- Science
- Newton’s Second Law Of Motion
- An automobile vehicle has a mass of 1500 kg. What must be the force between the vehicle and road if the vehicle is to be stopped with a negative acceleration of 1.7 m s–2?
- CBSE Class IX
- Science
- Newton’s Second Law Of Motion
- Why do you fall in the forward direction when a moving bus brakes to a stop and fall backwards when it accelerates from rest?
- CBSE Class IX
- Science
- Newton’s Second Law Of Motion
- A nucleus is at rest in the laboratory frame of reference. Show that if it disintegrates into two smaller nuclei the products must move in opposite directions.
- CBSE Class XI
- Physics
- Newton’s Second Law Of Motion
Questions Asked in CBSE Class IX exam
- Explain what the reasons for the following are.
(i) Einstein leaving the school in Munich for good.
(ii) Einstein wanting to study in Switzerland rather than in Munich.
(iii) Einstein seeing in Mileva an ally.
(iv) What do these tell you about Einstein?- CBSE Class IX
- A truly beautiful mind
- (i) The kind of person the doctor is (money, possessions)
(ii) The kind of person he wants to be (appearance, ambition)- CBSE Class IX
- The snake and the mirror
In Fig. 9.26, A, B, C and D are four points on a circle. AC and BD intersect at a point E such that ∠ BEC = 130° and ∠ ECD = 20°. Find ∠ BAC.
- CBSE Class IX
- Angle Subtended by an Arc of a Circle
- Name the two temples the author visited in Kathmandu.
- CBSE Class IX
- Kathmandu
Look up the dictionary entries for the words sympathy, familiarity, comfort, care, and surprise. Use the information given in the dictionary and complete the table.
Noun, Adjective, Adverb, Verb, Meaning:
sympathy
familiarity
comfort
care
surprise- CBSE Class IX
- If I were you
Concepts Used:
Laws of Motion
The laws of motion, which are the keystone of classical mechanics, are three statements that defined the relationships between the forces acting on a body and its motion. They were first disclosed by English physicist and mathematician Isaac Newton.
Newton’s First Law of Motion
Newton’s 1st law states that a body at rest or uniform motion will continue to be at rest or uniform motion until and unless a net external force acts on it.
Newton’s Second Law of Motion
Newton's 2nd law of motion deals with the relation between force and acceleration. According to the second law of motion, the acceleration of an object as built by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
Newton’s Third Law of Motion
Newton's 3rd law of motion states when a body applies a force on another body that there is an equal and opposite reaction for every action.