1. At what maximum speed can a car travel without skidding on a horizontal bend of a road with a radius of 20 m if the coefficient of friction of the car's tires to the road surface is 0.6?

2. The car is driving on a hilly road. The bend radius of the road hill is 90 m. At its highest point, the speed of the car is 15 m/s. The mass of the car is 2 tons. Draw the forces acting on the car!

Calculations:

a) The surface reaction force acting on the car at the highest point of the hill;

b) At what speed must the car move in order for the car to reach the highest point of the hill if passengers would be weightless!

3. A skier, whose mass including equipment is 60 kg, slides down a slope that forms 25 degree angle with the horizon.

a) What is the acceleration if the force of friction is neglected?

b) What is the acceleration if the frictional force is 45 N?

4. A load with a mass of 15 kg slides down an inclined surface that makes an angle a of 30 degrees with the horizon. The coefficient of friction between the load and the surface is 0.05. Calculate the force of friction, the acceleration of the block and the displacement made in 3 seconds!

5. A block slides smoothly along an inclined surface that makes an angle with the horizon. The angle of inclination decreases.

a) How does the coefficient of friction of the slide change between flat and lumpy?

b) Does the support reaction force change?

c) How does gravity change?

d) How does the force of sliding friction change?

Answer all of these questions above with following options: increases/decreases or doesn't change.

6. A tightrope walker with a mass of 60 kg is in the middle of the rope. Calculate with how much force F's tick the stretched rope, if the mass of the rope is so small that it can be neglected.

scale O Fi5 Fs F mg