Question

1. Consider the rocket sled below. The mass of the system is 2.1 x 103 k a. If the rocket sled decelerates at 196 m/s', what force is necessary to produce this deceleration? Assume the rockets are off. If the rocket sled starts from rest with only one rocket burning, what is the magnitude of its acceleration? Assume the thrust is T = 2.4 × 104 N and the force of friction opposing the motion is f-650 N With four rockets burning, why is the acceleration not 4 times the acceleration in (b)? b. c.

Answer 1

Given m = 2.1 times 10^3 kg (a) a = -196 m/s^2 force needed F = ma = 2.1 times 10^3 times 196 F = 411600 N Ans (b) T = 2.4 times 10^4 N friction force F_f = 650 N acceleration a = T - F_f/m = 2.4 times 10^-4 - 650/2.1 times 10^3 a = 11.12 m/s^2 Ans (c) If four rockets are burning T = 4 times 2.4 times 10^4 N a = T - F_f/m = 4 times 2.4 times 10^4 - 650/2.1 times 10^3 a = 45.40 m/s^2 acceleration is more than 4 times. because as thrust increase by using 4 rockets the friction force remain the same.