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A car with a mass of 800kg drives onto an arch bridge with a circular arc radius of 50m. (G is taken as 10m / S2) (l) When the car reaches the bridge top, the speed is 5m / s. how much pressure does the car put on the bridge? (2) At what speed does the car just take off without pressure on the bridge when it passes through the top of the bridge? (3) It is unsafe for the vehicle to have too little pressure on the ground. Therefore, from this point of view, the speed of the vehicle when crossing the bridge cannot be too large. For the same speed, is it safer to have a larger radius of the arch bridge arc, or is it safer to have a smaller radius? (4) If the radius of the arch bridge increases to the same as the radius r of the earth, how fast will the car fly off on the ground? (known earth radius is 6400km)
(1) When the car reaches the top of the bridge, the vertical direction is affected by gravity g and the supporting force n of the bridge
The pressure of the vehicle on the bridge top is equal to the supporting force n of the bridge top on the vehicle. When the vehicle crosses the bridge, it makes circular motion, and the resultant force of gravity and supporting force provides centripetal force;
According to Newton's second law: mg-N = MV2
r，
Yes: n = mg-mv2
r=（800 × 10-800 × fifty-two
50）N=7600N．
According to Newton's third law, the pressure of the car on the bridge is n '= n = 7600n, and the direction is vertical and downward
(2) When the car passes through the bridge top and just vacates without pressure on the bridge, then n = 0. The centripetal force of the car in circular motion is completely provided by its own gravity, so there are:
mg=mv
two
0
r
Get: v0=
gr=
ten × 50m/s=22.4m/s．
(3) From question 1: n ′ = mg-mv2
r. V at the same time, the greater the arch bridge radius r, the greater the n ', and the safer
(4) If the car wants to take off on the ground, the supporting force is zero, and the centripetal force provided by gravity is mg = MV
two
m
R
Get VM=
gR=
ten × six thousand and four hundred × 103m/s=8000m/s
Answer:
(1) When the vehicle reaches the bridge top, the speed is 5m / s, and the pressure of the vehicle on the bridge is 7600n
(2) When the car passes the bridge top at the speed of 22.4m/s, it just takes off without pressure on the bridge
(3) For the same speed, the larger the radius of arch bridge arc is, the safer it is
(4) If the radius of the arch bridge increases to the same as the radius r of the earth, the car will fly off on the ground at a speed of 8000m / s
A car with a mass of 800kg drives through a circular arch bridge with a radius of 50m and reaches the top of the bridge at a speed of 5m / s. how much pressure does the car put on the bridge at this time? If it is required that the pressure on the bridge when the car reaches the top of the bridge is exactly zero, how fast should the car reach the top of the bridge?
(1) As shown in the figure, when the car reaches the bridge top, the vertical direction is affected by gravity g and the supporting force n of the bridge. The pressure of the car on the bridge top is equal to the supporting force n of the bridge top to the car. When the car crosses the bridge, it makes a circular motion, and the resultant force of gravity and supporting force provides a centripetal force, that is, G-N = mv2r, n = G-F = mg-mv2r =
A car with a mass of 800kg drives onto an arch bridge with a circular arc radius of 50m. (G is taken as 10m / S2) (l) When the car reaches the bridge top, the speed is 5m / s. how much pressure does the car put on the bridge? (2) At what speed does the car just take off without pressure on the bridge when it passes through the top of the bridge? (3) It is unsafe for the vehicle to have too little pressure on the ground. Therefore, from this point of view, the speed of the vehicle when crossing the bridge cannot be too large. For the same speed, is it safer to have a larger radius of the arch bridge arc, or is it safer to have a smaller radius? (4) If the radius of the arch bridge increases to the same as the radius r of the earth, how fast will the car fly off on the ground? (known earth radius is 6400km)
(1) When the car reaches the top of the bridge, the vertical direction is affected by gravity g and the supporting force n of the bridge
The pressure of the vehicle on the bridge top is equal to the supporting force n of the bridge top on the vehicle. When the vehicle crosses the bridge, it makes circular motion, and the resultant force of gravity and supporting force provides centripetal force;
According to Newton's second law: mg-N = MV2
r，
Yes: n = mg-mv2
r=（800 × 10-800 × fifty-two
50）N=7600N．
According to Newton's third law, the pressure of the car on the bridge is n '= n = 7600n, and the direction is vertical and downward
(2) When the car passes through the bridge top and just vacates without pressure on the bridge, then n = 0. The centripetal force of the car in circular motion is completely provided by its own gravity, so there are:
mg=mv
two
0
r
Get: v0=
gr=
ten × 50m/s=22.4m/s．
(3) From question 1: n ′ = mg-mv2
r. V at the same time, the greater the arch bridge radius r, the greater the n ', and the safer
(4) If the car wants to take off on the ground, the supporting force is zero, and the centripetal force provided by gravity is mg = MV
two
m
R
Get VM=
gR=
ten × six thousand and four hundred × 103m/s=8000m/s
Answer:
(1) When the vehicle reaches the bridge top, the speed is 5m / s, and the pressure of the vehicle on the bridge is 7600n
(2) When the car passes the bridge top at the speed of 22.4m/s, it just takes off without pressure on the bridge
(3) For the same speed, the larger the radius of arch bridge arc is, the safer it is
(4) If the radius of the arch bridge increases to the same as the radius r of the earth, the car will fly off on the ground at a speed of 8000m / s
When a 2-ton vehicle travels to the highest point of an arch bridge with a radius r of 40m, G is taken as 10m / S2. Try to find out: ⑴ if the speed V1 = 10m / s, what is the centripetal acceleration of the vehicle? (2) when the connecting degree V2 of the finished vehicle is how large, there is no knife pressure on the bridge deck?
(1) The centripetal acceleration is equal to the square of the tangential velocity divided by the radius of curvature, where a = V2 / r = 2.5, the unit is m2 / s, and the direction points to the center of the circle
(2) If there is no pressure on the bridge deck, gravity should be fully provided as the centripetal force, i.e. m * g = m * V2 / R, and V2 = 20m / s
7. When a vehicle passes through the apex of the arch bridge, the speed is 10m / s, and the pressure of the vehicle on the bridge top is 3 / 4 of the vehicle weight Just through the top of the bridge, what is the maximum speed
The landlord's conditions are not complete. I'll make it up for you. Pay attention
According to the meaning of the topic, the speed is V (10m / s), the supporting force of the arch bridge to the vehicle is n, the vehicle mass is m, and the gravity acceleration is g
The radius of arch bridge is r
So mg-N = MV ²/ R resolves M
It's easy to do after knowing the quality
Because the car just passes through the vertex, only gravity and all gravity provide centripetal force, so n = 0
So mg = MV ²/ R's solution of V is the answer, where V represents the physical quantity
Tell me about the landlord
General middle school physics this problem type on this solution, take your time
So ! All right! o(∩_∩)o
When the vehicle passes through an arch bridge at the speed of 10m / s, the pressure of the vehicle on the bridge top is 3 / 4 times of the vehicle weight. If the vehicle is not affected by friction when driving to the bridge top along the bridge deck, what speed should the vehicle pass through the bridge top?.]
Force analysis: the resultant force of gravity support force acts as centripetal force
mg-N =mv^2/r
mg-3/4mg=mv^2/r
r=4v^2/g = 4* 10*10/10 = 40m
When there is no friction, that is, when the pressure on the bridge is 0, that is, the force analysis of the vehicle is that the vehicle only receives gravity without supporting force, and gravity acts as a centripetal force
mg=mv^2/r
Take m off g = 10, r = 40 and bring it into v. calculate it yourself. Don't be lazy
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- 20. 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!