answer #7 in detail please A person stands on a bathroom scale in a motionless e

Question

answer #7 in detail please

A person stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads 1.20 times the person's regular weight. Calculate the magnitude of the acceleration of the elevator. 7.84 m/s^2 4.90 m/s^2 none of these 9.80 m/s^2 1.96 m/s^2 A 80 N force is used to pull a 10 kg box at an angle of 60 degree. The box moves horizontally on the surface. What is the magnitude of the acceleration of the box if the coefficient of kinetic friction is mu_k = 0.20? 4.0 m/s^2 2.0 m/s^2 3.4 m/s^2 5.0 m/s^2 2.9 m/s^2 Which one of these statements is correct for a satellite moving in a stable circular orbit around the Earth? the speed of the satellite is independent of the mass of the satellite. the speed of the satellite is independent of the height above the Earth's surface. the speed of the satellite is independent of the radius of the orbit, the speed of the satellite is independent of the mass of the Earth. the speed of the satellite is independent of the universal gravitational constant. A car is driven 125 km west and then 45 km south. What is the magnitude and direction of the displacement of the car from the point of origin? 80 km ; 88.7 degree west of south 170 km ; 19.8 degree south of west 133 km ; 19.8 degree south of west 170 km ; 19.8 degree north of west 133 km ; 88.7 degree north of west

Explanation / Answer

5. the forces acting on the person are the normal force of the elevator acting up and the weight of the person acting down

the scale will record the magnitude of the normal force

newton's second law tells us

sum of forces = ma

here, this means

N - mg = ma

if N measures 1.20 of the normal weight, then we have

1.20mg-mg=ma

or a=-0.20g =-0.20*9.81 = -1.962 m/s/s

hence ans. is (e) 1.96 m/s2

6. d

7. For "orbit", centripetal acceleration = gravitational acceleration, or
v²/r = GM/r²
rearranges to
v = (GM/r)
where G = Newton's gravitational constant = 6.674e11 N·m²/kg²
and M = mass of Earth = 5.9736e24 kg
and r = radius of earth + altitude

hence speed of satelite is independent of mass of the satellite

hence ans. is a)

8. displacement = sqrt(1252 +452 ) =132.85 = 133 km

angle = tan-1 (45/125) =19.80 deg

hence ans. is c)

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