Whether someone likes it or not, we are gradually turning from car enthusiasts into banal users. And the reason is not only that modern technology has become almost maintenance-free. Many drivers are completely indifferent to how something works: it goes - and okay. But there are still a lot of those who yearn for garage discussions about technical topics. They offer them to stretch their brains.
1. Which of the following vehicles will be the first to compete in a race with a common start?
A - caterpillar tractor DT 75;
B - Boeing 747;
In - a bicycle;
Mr. Lada Grant.
The correct answer: A. At the time of simultaneous start, the DT 75 tractor has all the advantages. At lower gears, the traction force of the tracks reaches about 44, 300 N, and thanks to their excellent traction, it is confidently realized. The acceleration of a tractor weighing 6 tons is close to 0.75g. With Grants, the front tires are unloaded at the start, their grip decreases - even acceleration of 0.5g is not always possible to develop. A Boeing 747 is even worse: an aircraft with a take-off mass of 400 tons and a total thrust of four engines of 1, 130, 000 kN starts with an acceleration of only about 0.29 g. A cyclist is even slower!
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2. The sports car accelerates to 100 km / h in 3.0 s. What technical tricks can reduce this time to 1.0 s?
A - increase in engine power and torque;
B - reduction of aerodynamic drag coefficient Cx;
B - installation of an effective wing;
G - the problem has no solution: it is theoretically impossible.
The correct answer: B. The acceleration of the car is limited to the adhesion of tires to the road. With an adhesion coefficient of about 1.0 (dry asphalt), even an all-wheel drive vehicle does not allow acceleration to be higher than 1.0g. Be a motor even in a million forces, and Cx is zero. The minimum estimated acceleration time to hundreds will be 2.83 s.
There is only one thing left - to increase traction. In heated racing tires, the grip on dry asphalt is 1.4–1.6, but we are talking about standard wheels. Small wing of the racing formulas, pressing the wheels to the road, also will not help: at speeds up to 100 km / h they are ineffective. But if you install an inverted wing from a light aircraft with a take-off speed of less than 100 km / h to increase the downforce and thereby improve traction, this will solve the problem - in any case, theoretically.
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3. Which 10W 40 oil has a lower viscosity at 100 ° C - synthetic or mineral?
A - in synthetic;
B - the viscosity is the same;
B - in mineral;
G - both options are possible.
The correct answer: D. Both oils have the same range of viscosity at 100 ° C, but its specific values may vary. For the specified oil, this spread is from 12.6 to 16.3 mm² / s. Therefore, both options are theoretically possible.
4. Instead of a standard battery with an energy capacity of 50 Ah, another was installed - at 75 Ah. What are the negative consequences of such a replacement?
A - the average charge time will increase;
B - the load on the generator will increase;
B - there will be no negative;
G - the battery will constantly be undercharged.
The correct answer is: B. If you install a more capacious gas tank on the car, then why should it be, for example, half empty, and the gas pump - overloaded? So it is here: there will be no negative. When charging with constant voltage, excessive currents simply have nowhere to come from. The average charge time will also not change: it is determined by the degree of discharge of the battery, and not by the label on the case. And if the battery lost at start-up 1 Ah, the generator should return back exactly the same charge. And the recharge time of the capacity, of course, is independent.
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5. Which of the four-stroke engines listed below is self-balancing?
A - three-cylinder;
B - four-cylinder;
In - row "six";
G - V shaped "six".
The correct answer is: B. An engine is a lot of parts moving with acceleration. For each part, its mass, multiplied by acceleration, determines the force of inertia. And where there is strength and shoulder, moments arise. The specific distribution of forces and moments depends on the design of the motor, but both of them act on the engine mounts, causing vibration. If it is possible to achieve mutual destruction of the influence of these factors, then such a motor is called completely self-balanced.
Unfortunately, only a few engine designs are self-balanced in nature - among them, for example, a six-cylinder in-line engine and a 12-cylinder V-shaped. The second "four" were summed up by second-order inertia forces. The three-cylinder engine is even worse: the moments of centrifugal forces and inertial forces of two orders are to blame. And the V-shaped “six” is not balanced in time.
6. A pebble accidentally stuck in the rear wheel of a dissolution trailer towed on a flat, dry road. In which direction will he fly if he is freed?
A - always forward, in the direction of the car;
B - back, against the course of the car;
B - in any direction with equal probability;
G - forward, if at the moment of separation it does not touch the asphalt.
The correct answer is: G. A stone rotating with a wheel moves along a cycloid. (Bicycle wheels with luminous caps will demonstrate this curve in motion.) The free movement of the body begins tangentially to the path along which it moved before separation. This tangent always has a component in the direction of movement and never against. This means that the stone, flying out of the wheel, will fly in the direction of movement. Moreover, its speed can exceed the speed of the car by half! By the way, it is for this reason that such pebbles often fly into the tractor cabin.
The exception is the point of contact with the road at which the linear velocity is zero. If the stone is released at this moment, it will remain in place.
Why do stones sometimes break the windows of cars going behind? Firstly, if instead of asphalt there is soil or a slippery road, the drive wheel can stall and throw the stone in an arbitrary direction, including back. Secondly, the rear car can catch a stone flying in front of it. It is clear that the probability of catching such a “gift” from the same dissolution is much higher than from a passenger car, where a pebble can get lost in a wheel niche.
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7. What does the color of the coolant at the time of purchase say to the consumer ?
A - about the type of antifreeze: traditional, carboxylate, hybrid, lobrid;
B - about nothing;
B - on interchangeability;
G - about the freezing temperature.
The correct answer: B. Modern coolants are colorless. Coloring in one tone or another is the choice of a particular manufacturer, and not the consequence of any chemical reactions. Therefore, antifreezes of the same color may vary in composition, and multi-colored, on the contrary, may turn out to be the same.
8. Which of the listed parameters of gasoline is not standardized by the Technical Regulations?
A is the exact octane number;
B - resin content;
In - fractional composition;