Question

1) A 1200 kg car is broken down and is to be towed up a hill with angle of inclination of 5°. The coefficient of static friction between car and road is 0.1 and that of kinetic friction is 0.05. What minimum force by the tow-truck is required to start taking the car up the hill? Once the car starts moving up the hill, what minimum force is required to keep it moving up the hill?
2) A 40 kg block is on an inclined plane of angle 20°. Find the minimum horizontal force F that is required to stop the block from sliding down the slope considering:--- (a) the slope is
friction-less. (b) coefficient of static friction is 0.4
3) An object is moving at uniform velocity of 12 m/s on a horizontal surface. The coefficient of
kinetic friction = 0.3 . A force of 330 N is making the object move. Find the mass of the object.
4) An 20 kg object is moving on a horizontal surface. A person is pushing it horizontally with a
force of 60 N. The coefficient of kinetic friction = 0.1 At 9 am the velocity of the object is 2
m/s. How much distance will it travel in next 6 seconds?
I know the answers I just want the method ...
The answers 1) Fminimun=2239.2 N to set it in motion.
2)a)F minimum=68÷0.47= 144.7 ( approx)
b)F minimum=30.4÷0.47=64.7 ( approx)
3)m=110kg
4)distance=48 m
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thank you​

Answer 1

Explanation:

The forces N and mg cos(q) act perpendicular to the displacement, so their work done is zero!

The minus sign is due to force acting in opposite direction of displacement.

Solving for F