Question

Two astronauts are operating in a remote region of space. Their velocity and acceleration are both zero. The 80.0-kg astronaut pushes on the 60.0-kg astronaut with a force of 30.0-N for 0.5 seconds.

a. What is the momentum of the system before they push?

b. What impulse did the 80.0-kg astronaut apply to the 60.0-kg astronaut?

c. What is the velocity of the 60.0-kg astronaut after the push? See instruction C on page 1.

d. What is the velocity of the 80.0-kg astronaut after the push?

e. Calculate the momentum of the system after the push. Is this in line with your expectations?

f. How long will it take each astronaut to travel 10.0 m? (for this, you’ll need to use kinematics!)

Answer 1

here,

mass of asternaut 1 , m1 = 80 kg

mass of asternaut 2 , m2 = 60 kg

F = 30 N

t = 0.5 s

a)

the momentum of system before they push is ZERO

b)

the impulse delevired , I = F * t

I = 30 * 0.5 kg.m/s = 15 kg.m/s

c)

the final velocity of 2 be v2

I = m2 * ( v2 - 0)

15 = 60 * v1

v2 = 0.25 m/s

d)

the final velocity of 1 be v1

I = m1 * ( v1 - 0)

- 15 = 80 * v1

v1 = - 0.19 m/s

e)

using conservation of momentum

Pf = Pi = 0

f)

for 80 kg asternaut

the time taken , t1 = s / v1

t1 = 10 / 0.19 s = 53.3 s

for 60 kg asternaut

the time taken , t2 = s / v2

t2 = 10 / 0.25 s = 40 s