If a bus accelerates from 10 m/s to 15 m/s in 10 seconds with a force of 3000N what is its mass?
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Answer:
1
A car is traveling at 15m\s and comes to stop in 10s. If the average braking force is 3000N, what is the mass of the car?
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Ramon Molina
Answered June 21, 2017
F = m*a "Newton's 2nd Law of Motion.” For simplicity, assuming that we are neglecting the friction force of the road, then the following solution applies.
If an object is under a zero net force, it is either stationary or if moving, it moves at constant velocity. (Fe - Fb = 0) Acceleration is equal to zero,
Since the car's speed is initially constant; therefore, a1 = 0
ΣF = m*a ;
Fe - Fb = m*a1 = Fe - 3000N = m*(0) ;
Fe = 3000N + 0 = 3000N (engine force = Fe)
a = acceleration; Vf = final velocity; Vi = initial velocity; t = time in seconds
a2 = (Vf - Vi) / t = (0 - 15)/10 = -1.5 m/s^2 (decelerates)
ΣF = m*a
Fe - Fb = m*a2 = 0 - 3000N = m*(-1.5 m/s^2) (Fe at time of breaking -> Fe = 0)
m = (-3000kg )/(-1.5) = 2000 kg. (mass of the car and “m/s^2 cancels out.”)