Newton's 2nd Law - problems involving ramps and friction (with answers)

Steps:

- Draw a force diagram; deconstruct forces into x- and y-components
- Determine whether an acceleration/net force is present
- Write out the force equations in the x- and y-directions
- Use algebra to solve for the desired quantity

1. A 3.0 m long board has one end raised to a height of 60 cm to form an incline. A 4.0 kg mass is allowed to slide without friction down the entire length of the inclined plane.

a. What is the final speed of the mass when it reaches the bottom ? 3.4 m/s

b. If the mass is replaced with an 8.0 kg mass, what would be the new speed when it reaches the bottom?

3.4 m/s

2. A wooden block slides directly down an inclined plane, at a constant velocity of 6 m/s.

a. How large is the coefficient of kinetic friction if the plane makes an angle of 25º with the horizontal? 0.466

b. If the angle of incline is changed to 10º, how far will the block slide before coming to a stop? 64.3 m

3. A 10.0 kg box accelerates at 2.00 m/s^{2} as it slides down a ramp that makes an angle of 25.0 degrees with the horizontal. Find the coefficient of friction. 0.241

4. A 10.0 kg box is pulled up a 45 degree ramp at a constant velocity by a force of 90.0 N acting parallel to the ramp. Find the coefficient of friction. 0.296

5. a 10.0 kg box is pulled up a ramp that is at an angle of 20.0 degrees with the horizontal, with the rope that makes and angle of 30.0 degrees with the ramp. if pulling with a force of 70.0 N causes and acceleration of 2.00 m/s^{2}. Find the coefficient of friction. 0.124

6. A 10.0 kg box is pulled down a 45 degree ramp by a rope attached to the box that makes a angle of 30.0 degrees with the ramp. If a tension of 10.0 N causes the box to move at a constant velocity, what is the coefficient of friction for the box sliding on the ramp? 1.21

7. A car, with a mass of 1100kg, can accelerate on a level road from rest to 21 m/s in 14.0 s. What is the steepest frictionless slope this car can climb? 8.8^{o}

8. 10.0-kg box starts at rest and slides 3.5 m down a ramp inclined at an angle of 10 degrees with the horizontal. If there is no friction between the ramp surface and crate, what is the velocity of the crate at the bottom of the ramp? 3.2 m/s

9. An object is being pulled up a 15° incline against a frictional coefficient of 0.15, and requires a force of 835 N parallel to the surface of the ramp to move it at a constant speed. What is the weight of the object? 2068 N

10. The coefficient of static friction between a box and an inclined plane is 0.35. What is the minimum angle required for the box to begin sliding down the incline? 19^{o}

11. A package slides down a 135 m long ramp with no friction. If the package starts from rest at the top and is to have a speed no faster than 19 m/s at the bottom, what should be the maximum angle of inclination? 7.9^{o}