Kinetic Energy, EK=(1/2)mv2. Energy is conserved, so the work done by the brakes, W, must be equal to the change in kinetic energy of the car, ∆EK. Therefore: W = ∆EK = (1/2)1000(152-52) = 0.51000200 = 100000 = 1*105J. Since power P = W/T, the average power output of the brakes is equal to the total work done by the brakes over the time that the brakes are applied for, therefore: P = 100000/4 = 25000W.

8 0

3 years ago

In a physics lab, you attach a 0.200-kg air-track glider to the end of an ideal spring of negligible mass and start it oscillati

nikdorinn [45]

Answer:

k = 0.292 N / m

Explanation:

The glider with the spring forms a system with a simple harmonic movement, in this type of movement the angular velocity is given by

w = √ k / m

The angular velocity is related to the frequency and is related to the period

w = 2π f

f = 1 / T

We replace

2π / T = ra (k / m

T = 2π √ (m / k)

The period is the time of a complete oscillation, in this case the glider starts from the equilibrium point and returns for the first time, this corresponds to the middle of the period

½ T = 2.60 s

T = 2 2.60

T= 5.20 s

We clear the equation

T² = 4π² m / k

k = 4π² m / T²

Let's calculate

k = 4π² 0.200 / 5.20²

k = 0.292 N / m

6 0

3 years ago