Select the correct statement below. The acceleration of gravity, g, is lower in

Question

Select the correct statement below. The acceleration of gravity, g, is lower in Death Valley than atop Mt. Whitney which are separated by about 100 miles. Astronauts aboard an orbiting spacecraft experience weightlessness. Therefore they have zero mass. The weight of a 25 kg object is 250N When a race car driver takes a banked curve on the high (outer) side of a curve his maximum speed is mainly determined by the normal force of car on banked surface. If a jet airplane is coming out of a drive with a centripetal acceleration, = g_r, will experience a total force twice his weight. The centripetal frictional force that keeps a car moving around a level highway curve is greater at higher speeds.

Explanation / Answer

1) not correct.with this relation g'(acc.due to gravity at height) = g( 1- 2h/R) where h = height, R = radius of earth,

acceleration due to gravity decrease with height.So g will be high at valley.

2) not correct. Weightlessness means absence of weight ( W= mg= 0,here g= 0 not m(mass)). Weightlessness means no g force that an astronaut can feel,because of the free fall condition.

3) W = mg

= 25*10 = 250 N ( g = 10 m/s2)

correct

4) In case of banked road ,

horizontal component of normal force N*sin (theta) = m*V2/r

N*cos(theta) = mg

by solving we find value of V(speed) .hence maximum speed is determined by normal force on car.

So correct.

5) not correct.

centripetal acceleration = V2/ r = g -----------------given

F(force) = m*V2/r

= m*g = weight

6)centripetal force F = m*V2/r

if V(speed) increase then F will increase.

so correct.

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