Question

5:Two spacecraft in outer space attract each other with a force of 200 N. What would the attractive force be if they were twice as far apart?

a. 5 N b. 400 N c. 25 N d. 100N e. 50 N

7:In straight line motion the

a. acceleration is vertical and the displacement is horizontal b. acceleration is perpendicular to the displacement c. acceleration is vertical, while the displacement can be in any direction d. acceleration is always the same as the displacement e. None of the above

9:By what factor does the centripetal acceleration change if a car goes around a corner two times as slow?

a. 4 b. 2 c. 0.25 d. 9 e. it stays the same

10:A 5 kg ball is thrown horizontally at a speed of 20 m/s. At the same time a 10 kg ball is dropped from 0.5 meter lower. Ignoring air resistance, which ball hits the ground first?

a. none of the below b. hard to tell c. the 10 kg ball d. the 5 kg ball e. it is a tie

15:There are three forces acting on an object: 6 N to the left, 5 N to the right, and 1 N to the right. What is the net force acting on the object?

a. zero b. none of the above c. 6N left d. 1N right e. hard to tell

Answer 1

5) GIVEN F = 200 N

if = G m1m2/d^2

if d' = 2d

f' = Gm1m2/4d^2

f'/f = (Gm1m2/4d^2)/(Gm1m2/d^2) = 1/4

f' = f/4 = 200/4 = 50 N

7) in a straight line motion

if we apply a force on a body then the body displaces from one place to the another

force measn mass time acceleration

in a vertical motion a body is thrown upwards then displacement is opposite to the acceleration due to gravity

so answer is may is in the same direction of in the opposite direction

9) centripetal acceleration a = v^2/r

here v' = v/2

so acceleration becomes 0.25 time the previous value

10) time does not depedns on the mass

it depends on the only height

t = sqrt(2h/g)

for 5 kg ball

t1 = sqrt(2h/g)

for 10 kg ball its hegitht is lower than the 5 kg ball so 10 kg ball will reach the ground first

15) net force = 5+1-6 = 0 N