Advertisements
Advertisements
प्रश्न
In the case of negative work, the angle between the force and displacement is
विकल्प
0°
45°
90°
180°
Advertisements
उत्तर
180°
Explanation:
Work done is negative when a force acts opposite to the direction of displacement, i.e. the angle between the two directions is 180°.
संबंधित प्रश्न
Does the transfer of energy take place when you push a huge rock with all your might and fail to move it? Where is the energy you spend going?
A ball is placed on a compressed spring. What form of energy does the spring possess? On releasing the spring, the ball flies away. Give a reason.
A stone of mass 500 g is thrown vertically upwards with a velocity of 15 m/s. Calculate:
- the potential energy at the greatest height,
- the kinetic energy on reaching the ground, and
- the total energy at its half-way point.
State whether the object possess kinetic energy, potential energy, or both :
A ceiling fan in the off position ______________
State whether the object possess kinetic energy, potential energy, or both :
A stretched spring lying on the ground ____________.
What kind of energy is possessed by the following?
Water stored in the reservoir of a dam __________.
Fill in the blank with suitable word :
The sum of the potential and kinetic energies of a body is called __________ energy.
Fill in the blanks with suitable words:
When a ball is thrown upwards, ___________ energy is transformed into ___________ energy.
How much electrical energy in joules does a 100 watt lamp consume : in 1 second?
Five electric fans of 120 watts each are used for 4 hours. Calculate the electrical energy consumed in kilowatt-hours.
Write the energy transformations which take place in an electric bulb (or electric lamp).
A bulb lights up when connected to a battery. State the energy change which takes place :
The hanging bob of a simple pendulum is displaced to one extreme position B and then released. It swings towards centre position A and then to the other extreme position C. In which position does the bob have :
(i) maximum potential energy?
(ii) maximum kinetic energy?
A ball falls to the ground as shown below :
What is the potential energy of ball at B?
Which one of the following is not the unit of energy?
How much energy does a 100 W electric bulb transfer in 1 minute?
A microphone converts :
A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. The work done against the gravitational force will be (g = 10 m s–2)
An automobile engine propels a 1000 kg car (A) along a levelled road at a speed of 36 km h–1. Find the power if the opposing frictional force is 100 N. Now, suppose after travelling a distance of 200 m, this car collides with another stationary car (B) of the same mass and comes to rest. Let its engine also stop at the same time. Now the car (B) starts moving on the same level road without getting its engine started. Find the speed of the car (B) just after the collision.
A girl with having a mass of 35 kg sits on a trolley of mass 5 kg. The trolley is given an initial velocity of 4 m s–1 by applying a force. The trolley comes to rest after traversing a distance of 16 m. (a) How much work is done on the trolley? (b) How much work is done by the girl?
