Question

1. A satellite is launched with a constant thrust of 44600 N and has an acceleration of 7.01 m/s². Ignoring any air resistance, what is the mass of the satellite?

a. 649 kg.
b. 6.36×10³ kg.
c. 1.60×10⁴ kg.
d. 2.65×10³ kg.

2. A 1260 kg car slams on it's breaks and skids down a road sloped at 13.6° from the horizontal. The coefficient of kinetic friction between the tires and the road is 0.430. What is the magnitude of acceleration of the car while it is skidding?

a. 1.91 m/s².
b. 6.40 m/s².
c. 5.59 m/s².
d. 1.79 m/s².

Answer 1

1. Resultant Force = Thrust - Weight of satellite

Also Resultant Force = mass*acceleration

ma = Thrust - Weight of Rocket

ma = 44600 - mg

m(a+g) = 44600

mass = 44600/(9.81+7.01) = 44600/16.82

Mass = 2651.6 kg = 2.65*10³ kg

ANSWER: Option d. 2.65*10³ kg

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2mass of car = 1260 kg

weight of car mg is split into two mgsin13.6 and mgcos13.6

Frictional force Fr is acting opposite to movement = umgcos13.6

Net Force = mass*acceleration

mgsin13.6 - Fr =ma

mgsin13.6 - umgcos13.6 = ma (cancel mass m)

9.81(sin13.6 -ucos13.6) = a

-9.81*0.1828 =a

acceleration = -1.79m/s² (negative sign is because of dcceleration)

ANSWER : Option d.1.79m/s²