![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
The maximum speed of an automobile with a rated power of 80kW on a straight highway is 20m / s, and the mass of the automobile is 2 × 103kg. If the vehicle moves in a straight line with uniform acceleration from standstill, the acceleration is 2m / S2, and the resistance remains unchanged during the movement, try: (1) What is the constant resistance of the car? (2) How long does it take to move in a straight line with uniform acceleration?
(1) When the resistance is equal to the traction force and the maximum speed of the vehicle is VM = PF, there are: F = PVM = 8000020 = 4000N; (2) According to Newton's second law: f-f = Ma; The solution is: F = ma + F = 2000 × The maximum speed of 2 + 4000 = 8000n uniform acceleration is: v = pf = 800000 = 10m / s, so uniform acceleration
When a car with M = 2.0 * 10 cubic kg is driving on a horizontal highway and passing a curve with radius r = 50m, if the speed v = 72km / h, will the car slip? (it is known that the maximum static friction force between tire and road surface Fmax = 1.4 * 10 to the fourth power n)
Centrifugal force calculation formula: F = m * V * V / r = 2000 * 20 * 20 / 50 = 16000n
I'll tell you the maximum static friction. Plus the car has at least four tires multiplied by four, which is equal to 560000n, which is much greater than the centrifugal force. It won't sideslip. Unless your car has a tire, it will sideslip!
If it is a multiple-choice question, choose "no sideslip" after reading the topic. If you want a radius of 50m, it is 100m in diameter, that is, a route drawn in a circle with a 100m race track. A car will not sideslip on asphalt or cement pavement at 72km / h, unless it is on ice!
A vehicle with a mass of 2000kg runs on a horizontal highway with a rated power P = 60000w, and the resistance of the vehicle is constant At a certain time, the speed of the vehicle is 20m / s, the acceleration is 0.5m/s2, and G is taken as 10m / S2 (1) Seeking resistance (2) The maximum speed a car can reach (3) What is the acceleration when the speed is 10m / S (4) If the vehicle does not run at rated power, but starts to do a = 1m / S2 uniformly accelerated linear motion from standstill, how long can this process be maintained
(1) F is the power, f is the resistance, P = f * V, f = P / v = 60000 / 20 = 3000nf-f = ma 3000-f = 2000 * 0.5 f = 2000N (2) when f = f, a is 0 and the speed is the maximum. Because f is constant at 2000N, f = F = 2000N, v = P / F = 60000 / 2000 = 30m / S (3) when V is 10m / s, f = P / v = 60000 / 10 = 6000nf-f = ma 6000-2000 = 2
A vehicle with a mass of 2000kg started from standstill, drove 50m on the road, and the speed increased to 36km / h, Suppose the traction force of the vehicle is 7200n, find (1) how much work does the traction force F do? (2) How much power can the car increase? (3) What is the resistance of the car? (kinetic energy theorem)
17200x50,2,1 / 2x2000x (10) square, 3, first find a = 5, (f traction - f resistance) = ma
When a vehicle with M = 2.0 * 10 ^ 3kg is driving on a horizontal highway and passing a curve with radius r = 50m What is the maximum speed allowed? Known maximum static friction between tire and road surface Fmax = 1.4 * 10 ^ n
The centripetal force formula is f = (MV ^ 2) / r = MRW ^ 2,
To drive safely, the centripetal force needs to be less than the friction force so that it will not be thrown out
Therefore, it is known that f = (MV ^ 2) / r = MRW ^ 2
The mass is 1.0 × The freight car with the 6th power kg of 10 runs on the horizontal track. After 50s, the speed increases from 72km / h to 144km / h. It is assumed that the resistance of the train is 0.01 times, calculate the traction force of the locomotive. (G is taken as 10m / S2)
72km/h=20m/s,144km/h=40m/s
Then acceleration a= Δ v/ Δ t=(40-20)/50=0.4m/s^2
Set the traction force as F and the resistance f = 0.01mg = 10 ^ 5N
F-f=ma,F=ma+f=5*10^5N
That is, the traction force is 5 * 10 ^ 5N
RELATED INFORMATIONS
- 1. A car with a mass of 0.8 * 10 3 kg drives at a constant speed of 72km / h on a straight highway, The resistance of the vehicle is one tenth of the gravity, G is 10N / kg 1 work done by car traction within 5min 2 power of car at this time
- 2. A car with a mass of M = 1000kg drives through a circular arch bridge with a radius of 10m, and the pressure on the bridge is just zero when it reaches the top of the bridge A car with a mass of M = 1000kg drives through a circular arch bridge with a radius of 10m. When reaching the bridge top, the pressure on the bridge is just zero, and the car does not leave the bridge deck. What should be the speed when reaching the bridge top? (the value of G is m / S ^ 2) I hope I can paste the problem-solving steps!
- 3. Direction of friction force on running automobile tire A 4WD vehicle runs at a uniform speed on a horizontal road, regardless of air resistance. Its tires are pulled by the forward friction, but because there is still rolling friction, its tires are also subjected to the backward friction. However, the friction is only opposite to the relative movement trend. How can the friction be both forward and backward?
- 4. For the vehicle traveling at the speed of 18m / s, after emergency braking, make uniform deceleration and linear motion, and its acceleration is 6m / S2. Calculate the distance the vehicle passes within 6S after braking
- 5. In the plane rectangular coordinate system, given a (- 3,4) B (- 1, - 2) O (0,0), find the area of triangle abo
- 6. Make a triangle with points a (1,0), B (2,0) and C (1,3) as vertices in the plane rectangular coordinate system. (1) calculate the area of triangle ABC; (2) Set triangle ABC Add 2 to the abscissa of the three vertices to find the area of the new triangle; (3) Add 1 to the ordinates of points a, B and C to obtain the area of the new triangle; (4) The coordinates of the three vertices of triangle ABC are expanded to twice the original, and the area of the new triangle is obtained
- 7. It is known that the three sides of a triangle are: 2, 3 and 4. Is this an obtuse triangle? Why?
- 8. The speed before braking is 5m / s, and the acceleration of 0.4m/s is obtained when braking. Find: (1) (2) (3) write the specific steps The speed before braking is 5m / s, and the acceleration of 0.4m/s is obtained when braking Find: (1) the sliding distance within 20s after braking; (2) The time from opening the brake to when the displacement of the vehicle is 30m; (3) Sliding distance of vehicle within 2.5s of standstill ***Be sure to write down the specific steps
- 9. In a triangular ABC, the lengths of the three sides are 15, 17 and 8 respectively. What is the area of the triangular ABC? Such as title
- 10. On a straight highway, the speed of a car is 15m / s. It starts braking at a certain time. Under the action of resistance, the car moves at an acceleration of 2m / S2. How far does the last car leave the starting braking point 10 s after braking?
- 11. In uniform circular motion, why the greater the acceleration, the faster the direction of velocity changes. (it is best to use illustration)
- 12. Does the dog pull the sled in a uniform circular motion with constant acceleration?
- 13. The magnitude of sliding friction is related to the pressure on the contact surface and the roughness of the contact surface The size of sliding friction is related to the pressure on the contact surface and the roughness of the contact surface. Please design a simple experiment to verify that the size of sliding friction is related to the pressure on the contact surface. In addition to long wooden boards, there are iron blocks, aluminum blocks and wood blocks of the same quality. Each block is fixed with a small metal hook for traction, Fixed pulley, spring dynamometer, several thin wires
- 14. A student is holding a small umbrella in the rain. The radius of the edge of the umbrella is R and higher than the horizontal ground h. When the umbrella rotates at an angular speed W, the umbrella throws out from the edge of the umbrella and forms a circle on the ground. What is the radius of the circle?
- 15. Can potatoes specially made for potato planting eat I ate specially made green potatoes. Does it affect my health
- 16. A horizontal disc with radius r rotates at a constant angular velocity W. a person with mass m wants to go from the edge of the disc to the center of the disc. What is the attack of the disc on him? The answer is - 1 / 2MR ^ 2W ^ 2
- 17. The wood block with mass m is placed on a smooth horizontal plane, and the bullet with mass m is fired in the horizontal direction at velocity V0 and finally remains in the wood block and moves with the wood block in V A,FL=1/2Mv2 B.Fs=1/2mv2 C.Fs=1/2mv02-1/2(M+m)v2 D.F(L+s)=1/2mv02-1/2mv2 The wood block with mass m is placed on a smooth horizontal plane, and the bullet with mass m is fired in the horizontal direction at velocity V0 and finally remains in the wood block and moves with the wood block in V. It is known that when the bullet is stationary relative to the wood block, the wood block advances L, and the depth of the bullet entering the wood block is s. if the resistance F of the wood block to the bullet is constant, then
- 18. Why should the trajectory of the particle with the longest flight time in a magnetic field be tangent to the boundary of the magnetic field
- 19. As for friction, the correct one in the following statement is () A. The direction of sliding friction is always opposite to the direction of motion of the object B. Sliding friction always hinders the relative motion between objects C. The magnitude of the friction force must be proportional to the pressure between the contact surfaces D. The direction of friction can be perpendicular to the direction of motion of the object
- 20. When the wood block with mass of M = 1kg is stationary on the platform with height of H = 1.2m, the dynamic friction coefficient between the wood block and the platform As shown in the figure, the wood block with mass of M = 1kg is still at the height of H = 1.2m Dynamic friction coefficient between wood block and platform on platform μ= 0.2, with horizontal thrust f = 20n, Remove the wood block when it has a displacement of S1 = 3M, and fly out of the platform when it slides again and S2 = 1m, Find the speed of the wooden block when it falls to the ground? ( )