A car of mass M moves with a constant speed `v` over a horizontal flat surface. What force is exerted by the car on the bridge in the case, as it passes the middle point of the bridge ?

A body is moving at constant speed over a frictionless surface. What is the work done by the weight?

A car of mass 1000 kg moving with a velocity of 36 km/h comes to rest in 5 seconds. What is the force exerted on the car?

One end of a string of length t is connected to a particle of mass m and the other to a small peg on a smooth horizontal table. If the particle moves in a circle with speed v the net force on the particle (directed towards the centre) is : T is the tension in the string. [Choose the correct alternative].

A car is moving at a constant speed of 60kmh^-1 on a straight road. Looking at the rear view mirror, the driver finds that the car following him is at a distance of 100 m and is approaching with a speed of 5 kmh^-1 . In order to keep track of the car in the rear, the driver begins to glance alternatively at the rear and side mirror of his car after every 2 s till the other car overtakes. If the two cars were maintaining thier speed, whihc of the following statement is/are correct?

Two heavy spheres each of mass 100 kg and radius 0.10 m are placed 1.0 m apart on a horizontal table. What is the gravitational force and potential at the mid point of the line joining the centres of the spheres ? Is an object placed at that point in equilibrium? If so, is the equilibrium stable or unstable ?

A machine gun of mass M fires n bullets per second .The mass and speed of each bullet is m and v respectively. Then force exerted on the machine gun is :

On complete combustion a litre of petrol gives off heat equivalent to 3 xx 10^7 J . In a test drive a car weighing 1200 kg, including the mass of driver, runs 15 km per litre while moving with a uniform speed on a straight track. Assuming tha friction offered by the road surface and air to be uniform, calcuate the force of friciton acting on the car during the test drive, if the efficiency of the car engine were 0.5.