Contact forces are those that arise from physical contact between two objects, such as friction, air resistance, viscous force, and buoyant force. Gravitational force, on the other hand, is a non-contact force. It acts at a distance between objects with mass, such as between the Earth and an object on its surface.
The correct option is (E) : gravitational force
Gravitational force is not a contact force. It acts at a distance without physical contact between the objects involved.
The other forces listed — frictional force, buoyant force, air resistance, and viscous force — all arise due to contact between bodies.
Answer: gravitational force
The driver sitting inside a parked car is watching vehicles approaching from behind with the help of his side view mirror, which is a convex mirror with radius of curvature \( R = 2 \, \text{m} \). Another car approaches him from behind with a uniform speed of 90 km/hr. When the car is at a distance of 24 m from him, the magnitude of the acceleration of the image of the side view mirror is \( a \). The value of \( 100a \) is _____________ m/s\(^2\).