1.  A semi-tractor-trailer truck consists of a tractor unit (m_tractor=8,000 kg) and two semi-trailers to carry freight (m_trailer=10,000 kg). The tractor is capable of exerting 7.00 x 10⁵ N force on the road to accelerate the truck forward.

What is the force of kinetic friction (in Newtons) between the truck and the road, if no cargo is loaded? Ignore the force of drag.

Useful information:

The static friction coefficient between the truck and a dry road is μ_S=0.9

The kinetic friction coefficient of the truck on a dry road is μ_K=0.7

The surface area of the front of the truck is A=10m²

The drag coefficient of the truck is C=35.5

The density of the air is ρ =1.21 kg/m³

^.

2. For the same truck from question 1, ignoring the possible lack of traction due to a bad distribution of weight, does it matter how the cargo is distributed when loading the semi-trailers? For instance, if we put all the cargo in one of the trailers, will that affect the total force of kinetic or static friction? Although not needed for this quiz, think about how you would prove that.

Yes

Only the kinetic friction will be affected.

No

Only the static friction will be affected.

3. For the same truck from problem 1, if the truck is making a curve with 0.50 km of diameter at 72km/h, what is the centripetal acceleration of the truck? Express the results in m/s².

4. For the same truck from question 1, what is the acceleration of the truck (in m/s²) if the truck is going up a hill with an inclination of 30^o? Consider that the truck is already moving. Ignore the force of drag. Don’t forget to include the force of gravity.

5. Consider that the truck from question 1 is now loaded with 20,000 kg on trailer 1, and 25,000 kg on trailer 2. What is the force of kinetic friction acting on the truck (in Newtons)? Ignore the force of drag.

6. For the same truck from question 5. Considering the drag force acting on the truck, what is the terminal velocity of the truck (in m/s), if the truck is going down a hill with an inclination of 30^o? Do NOT ignore friction. Don’t forget to include the force of gravity.

7. For the same truck from question 5. If the truck is making a curve with 0.80 km of diameter at 72km/h, what is the centripetal acceleration of the truck (in m/s²)? Express the results in m/s².

8.

There is an incline and a block of mass 20kg on it as shown in the figure. The angle of the slope is 40^o.

When the horizontal force F whose magnitude is 360N is applied as shown in the figure, the block stays stationary on the slope. What is the magnitude of the normal force acting on the block from the slope?

Group of answer choices

231 N

150 N

382 N

331 N

250 N

9.

Modern roller coasters have vertical loops like the one shown in the Figure. The radius of curvature is smaller at the top than on the sides so that the downward centripetal acceleration at the top will be greater than the acceleration due to gravity, keeping the passengers pressed firmly into their seats. What is the speed of the roller coaster at the top of the loop if the diameter of curvature there is 40.0 m and the downward acceleration of the car is 20 m/s²?

Group of answer choices

15 m/s

19.4 m/s

14.8 m/s

28.3 m/s

20 m/s

10. A 30.0 m tall hollow aluminum flagpole is equivalent in strength to a solid cylinder 4.00 cm in diameter. A strong wind bends the pole much as a horizontal force of 700 N exerted at the top would. How far (in mm) to the side does the top of the pole flex? Assume the Shear modules to be equal to 2.5x10¹⁰ N/m².
 
 
 

tractor semi-trailer 1 semi-trailer 2