(a) If the rocket sled shown in Figure 4.31 starts with only one rocket burning, what is the magnitude of its
acceleration? Assume that the mass of the system is 2100
kg, the thrust T is 2.4 x 104 N, and the force of friction
opposing the motion is known to be 650 N. (b) Why is the
acceleration not one-fourth of what it is with all rockets
burning?

An astronaut in space cannot use a scale or balance to weigh objects because there is no gravity. but she does have devices to measure distance and time accurately. she knows her own mass is 77.4 kg , but she is unsure of the mass of a large gas canister in the airless rocket. when this canister is approaching her at 3.50 m/s , she pushes against it, which slows it down to 1.30 m/s (but does not reverse it) and gives her a speed of 2.60 m/s . what is the mass of the canister?