Question

A cue stick exerts a force of 200 N for 10?3 s to a stationary billiard...

A cue stick exerts a force of 200 N for 10?3 s to a stationary billiard ball (A) with
mass m. Then this billiard ball (A) hits another billiard ball (B) with same mass
and which is at rest initially. After the collision, the billiard ball (B) moves with a
speed vB =
p
2 m/s at an angle 45 degree with respect to the axis of the incoming
ball (A). Assuming no friction between the billiard balls and the table, and assuming
the collision is completely elastic: (cos 45 = sin 45 =
p
2=2)
15. What is the angle between directions of two moving balls after the collision?
(a) 30 (b) 60 (c)
p
2 30 (d) 0 (e) 90
16. What is the mass m of each billiard ball?
(a)
p
200 kg (b) 1 kg (c) 0.2 kg (d) 0.1 kg (e)
p
2 kg
17. What is the maximum radius of a planet with mass 9 1024 kg, in order that an object thrown out from this planet with
a speed c would not overcome the gravitational force? (c = 3 108 m/s, Universal gravitational constant G = 7 10?11
Nm2/kg2)
(a) 7 mm (b) 60 mm (c) 700 mm (d) 14 mm (e) 120 mm