Question 5 of 5 Map dub sapling this question was written by Sean Cordry at Walt

Question

Question 5 of 5 Map dub sapling this question was written by Sean Cordry at Walters State Community College After ten years tire of it. So she bought a rocket pack. (The mass of Brenda and her rocket pack is 70.0 kg of a two-hour commute, Brenda has gotten sick and Answer the three questions below using three significant figures. (Let g 9.81 m/s2) Part A How much upward force must the rocket provide in order for Brenda to hover motionless in the air? Number Part B: If the upward force from the rocket were equal to FR 1030 N, what is Brenda's upward accleratin? Number m/s Part C: In order to be safe when she is landing at the end of her commute, her downward acceleration must be a =-0.400 m/s2. How much thrust doest the rocket need to supply in order to achieve such an acceleration O Previous @Next Save And Ext

Explanation / Answer

(a)

the two forces acting on brenda at the moment of launch are the thrust upwards and the weight downwards

weight is the force due to gravity (W = m g)

the resultant force on each rocket is calculated using the equation resultant force = thrust – weight

mass m = 70 kg

weight W = (70) (9.81)

= 686.7 N

so to keep her motionless in air the thrust must be given greater than her weight

so the thrust must be approximately 700 N

(b)

F = 1030 N

m = 70 kg

if a is the acceleration from newtons second law of motion

from F = m a

a = F / m

= 14.71 m / s2

(c)

reultant force = upward thrust - weight

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