Please select a subject first
Advertisements
Advertisements
Answer in one sentence.
Define friction.
Concept: undefined >> undefined
Answer in one sentence.
Why force of static friction is known as ‘self-adjusting force’?
Concept: undefined >> undefined
Advertisements
Answer in one sentence.
Name two factors on which the coefficient of friction depends.
Concept: undefined >> undefined
State any four methods to reduce friction.
Concept: undefined >> undefined
Answer in short.
What is rolling friction? How does it arise?
Concept: undefined >> undefined
Answer in short.
Explain how lubricants help in reducing friction.
Concept: undefined >> undefined
Answer in short.
State the laws of static friction.
Concept: undefined >> undefined
Answer in short.
State the laws of kinetic friction.
Concept: undefined >> undefined
Answer in short.
State advantages of friction.
Concept: undefined >> undefined
State disadvantages of friction.
Concept: undefined >> undefined
Long answer type question.
Define coefficient of static friction and coefficient of kinetic friction. Give the necessary formula for each.
Concept: undefined >> undefined
Calculate the coefficient of static friction for an object of mass 50 kg placed on horizontal table pulled by attaching a spring balance. The force is increased gradually it is observed that the object just moves when spring balance shows 50 N.
Concept: undefined >> undefined
Answer the following.
A block of mass 37 kg rests on a rough horizontal plane having coefficient of static friction 0.3. Find out the least force required to just move the block horizontally.
Concept: undefined >> undefined
A body of mass 37 kg rests on a rough horizontal surface. The minimum horizontal force required to just start the motion is 68.5 N. In order to keep the body moving with constant velocity, a force of 43 N is needed. What is the value of coefficient of static friction?
Concept: undefined >> undefined
The internal resistance of a cell of emf 2 V is 0.1 Ω it is connected to a resistance of 0.9 Ω. The voltage across the cell will be ______.
Concept: undefined >> undefined
Solve the following problem.
A battery after a long use has an emf 24 V and an internal resistance 380 Ω. Calculate the maximum current drawn from the battery? Can this battery drive starting motor of car?
Concept: undefined >> undefined
Solve the following problem.
A battery of emf 12 V and internal resistance 3 Ω is connected to a resistor. If the current in the circuit is 0.5 A,
- Calculate resistance of resistor.
- Calculate terminal voltage of the battery when the circuit is closed.
Concept: undefined >> undefined
Answer the following question.
Describe what is meant by order of magnitude.
Concept: undefined >> undefined
Justify the statement, “Work and energy are the two sides of a coin.”
Concept: undefined >> undefined
Answer the following question.
From the terrace of a building of height H, you dropped a ball of mass m. It reached the ground with speed v. Is the relation mgh = `1/2"mv"^2` applicable exactly? If not, how can you account for the difference? Will the ball bounce to the same height from where it was dropped?
Concept: undefined >> undefined
