A 2kg mass moving at 10m/s slows to speed of 4m/s while sliding across a rough horizontal surface. The work done by friction is most nearly

A. 116j
B -116J
C. 84j
D. -84j
E. -16j

To find the work done by friction, you can use the formula:

Work = Force x Displacement x cos(θ)

In this case, the force is the force of friction, the displacement is the distance the object moves, and θ is the angle between the direction of the force and the direction of displacement. Since the surface is horizontal, the angle θ is 0 degrees, and cos(0°) = 1. So the formula simplifies to:

Work = Force x Displacement

To calculate the force of friction, we need to use the equation:

Force of friction = μ * Normal force

where μ is the coefficient of friction and Normal force is the force exerted by the surface perpendicular to the direction of motion.

Since the object is moving horizontally on a rough surface, the Normal force is equal to the weight of the object. The weight is given by:

Weight = mass x gravity

where the mass of the object is 2 kg and the acceleration due to gravity is approximately 9.8 m/s².

Weight = 2 kg x 9.8 m/s² = 19.6 N

Now we can calculate the force of friction using the given information. However, to do that, we need to know the coefficient of friction, which is not provided in the given question. Without this information, it is not possible to determine the exact value of the work done by friction.

Therefore, the answer cannot be determined with the information given.