If you exert a force of 60 N on a car, it moves at a constant velocity. (i.e there is a frictional force of 60 N) What is its mass when you exert 80 N on it, it accelerates from rest to 2.0 m/s in 100 seconds?
v=at => a =v/t =2/100=0.02 m/s²
0=F1-F(fr) =>F(fr)=F1,
ma=F2-f(fr)= F2-F1,
m=( F2-F1)/a=(80-60)/0.02=1000 kg
To solve this problem, we can use Newton's second law of motion, which states that the net force acting on an object is equal to the mass of the object multiplied by its acceleration.
In the first scenario where the car is moving at a constant velocity, the force exerted on the car is balanced by the frictional force. Since the car is moving at a constant velocity, we know that the net force is equal to zero. Therefore, we can set up the equation as:
60 N - frictional force = 0 N
Since the frictional force is equal to 60 N, we can rewrite the equation as:
60 N - 60 N = 0 N
In the second scenario where the car accelerates from rest to 2.0 m/s, we can apply Newton's second law of motion. The net force acting on the car is equal to the mass of the car multiplied by its acceleration. We can set up the equation as:
80 N - frictional force = mass * acceleration
Since the frictional force is equal to 60 N and the acceleration is given as 2.0 m/s in 100 seconds, we can rewrite the equation as:
80 N - 60 N = mass * (2.0 m/s / 100 s)
Simplifying the equation further:
20 N = mass * (0.02 m/s²)
Now, divide both sides of the equation by 0.02 m/s²:
mass = 20 N / 0.02 m/s²
mass = 1000 kg
Therefore, the mass of the car is 1000 kg when a force of 80 N is exerted on it and it accelerates from rest to 2.0 m/s in 100 seconds.