Laws of Motion - Online Test
Q1. Impulse is a
Answer : Option D
Explaination / Solution:
Since force is a vector quantity, impulse is also a vector in the same direction.
Impulse J produced from time t1 to t2 is defined to be
where F is the resultant force applied from t1 to t2
force is related to momentum p by
F = dp/dt
therefore,
where is the change in linear momentum from time t1 to t2
Q2. Newton’s third law states that
Answer : Option D
Explaination / Solution:
When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body. According to Newton's law for every action there is always opposit and equal reaction or the mutual actions of two bodies upon each other are always equal and opposite in direction.
Q3. According to Newton's third law of motion, the action and reaction forces are
Answer : Option A
Explaination / Solution:
When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.To every action there is always opposed an equal reaction or the mutual actions of two bodies upon each other are always equal and opposite in direction.
Q4. According to the law of conservation of momentum,
Answer : Option A
Explaination / Solution:
when no external forces acts on a system of several interacting particles, then the total momentum is conserved.
Q5. When bodies are in contact with each other then
Answer : Option A
Explaination / Solution:
according to newton's third law of motion for every action there is always equal and opposite reaction or the mutual actions of two bodies upon each other. Whenever two objects interact with each other, then the pair of forces acting on them are equal in magnitude and opposite in direction.
Contact forces are mutual forces (action and reaction)
Q6. Friction is
Answer : Option B
Explaination / Solution:
Whenever a body of mass m moves or tends to move over the surface of another body, then the opposite force acts parallel to the surface contact which opposes the relative motion.
Q7. Rolling friction is
Answer : Option D
Explaination / Solution:
As the area of contact is less in the case of rolling than in the case of sliding. In rolling surface of contact do not rub each other. The velocity of the point of contact with respect to the surface remains zero all the time although the Centre of mass of the wheel moves forward. Hence rolling friction is negligible in comparison to static friction.
Q8. The magnitude of the centripetal force is given by
Answer : Option D
Explaination / Solution:
Centripetal force is a force which acts on a body moving in a circular path and is directed towards the Centre around which the body is moving. Any motion in a curved path represents accelerated motion, and requires a force directed toward the center of curvature of the path. This force is called the centripetal force which means "center seeking" force.
The force has the magnitude
Q9. The centripetal force required for circular motion of a car such as taking a sharp turn is provided by
Answer : Option C
Explaination / Solution:
it is the force of friction that acts between tyres and road.
Q10. In which of the following cases is the net force non zero?
Answer : Option B
Explaination / Solution:
The force acting on a coin is due to gravitational force which causes an acceleration in downward direction.
