Molecular Physics | Thermodynamics Answers

An iron railway line is 30m long at a temperature of 27oC. What would be the length of the 

railway line when the temperature increases to 57oC? The coefficient of linear expansion of 

iron is 1.2 x 10-5 oC-1

A 2.0-g particle moving at 6.2 m/s makes a perfectly elastic head-on collision with a resting 1.0-g object.

(a) Find the speed of each particle after the collision.

2.0 g particle ___    m/s

1.0 g particle ___   m/s

(b) Find the speed of each particle after the collision if the stationary particle has a mass of 10 g.

2.0 g particle  ___   m/s

10.0 g particle ___   m/s

(c) Find the final kinetic energy of the incident 2.0-g particle in the situations described in parts (a) and (b).

KE in part (a) ___  J

KE in part (b) ___    J

Consider a frictionless track as shown in the figure below. A block of mass m₁ = 5.55 kg

 is released from . It makes a head-on elastic collision at  with a block of mass m₂ = 12.5 kg

 that is initially at rest. Calculate the maximum height to which m₁ rises after the collision.

___m

A spaceship's orbital maneuver requires a speed increase of 1.35 ✕ 10³ m/s. If its engine has an exhaust speed of 2.25 ✕ 10³ m/s, determine the required ratio M_i/M_f

 of its initial mass to its final mass. (The difference M_i − M_f

 equals the mass of the ejected fuel.)

____.

A bullet of mass m = 8.00 g is fired into a block of mass M = 150 g that is initially at rest at the edge of a table of height h = 1.00 m (see figure below). The bullet remains in the block, and after the impact the block lands d = 2.30 m from the bottom of the table. Determine the initial speed of the bullet.

___ kg/s

Three ice skaters meet at the center of a rink and each stands at rest facing the center, within arm's reach of the other two. On a signal, each skater pushes himself away from the other two across the frictionless ice. After the push, skater A with mass m_A = 70.0 kg

 moves in the negative y-direction at 2.00 m/s and skater B with mass m_B = 85.0 kg

 moves in the negative x-direction at 3.50 m/s. Find the x- and y-components of the 75.0 kg skater C's velocity (in m/s) after the push.

v_Cx=__ m/s

v_Cy=___ m/s

Squids are the fastest marine invertebrates, using a powerful set of muscles to take in and then eject water in a form of jet propulsion that can propel them to speeds of over 11.5 m/s. What speed (in m/s) would a stationary 2.00 kg squid achieve by ejecting 0.115 kg of water (not included in the squid's mass) at 3.50 m/s? Neglect other forces, including the drag force on the squid.

___m/s

The front 1.20 m of a 1,250-kg car is designed as a "crumple zone" that collapses to absorb the shock of a collision.

(a) If a car traveling 26.0 m/s stops uniformly in 1.20 m, how long does the collision last?

___ s

(b) What is the magnitude of the average force on the car?

 ___N

(c) What is the magnitude of the acceleration of the car? Express the acceleration as a multiple of the acceleration of gravity.

 ___ g

A tennis player receives a shot with the ball (0.0600 kg) traveling horizontally at 58.0 m/s and returns the shot with the ball traveling horizontally at 36.8 m/s in the opposite direction. (Take the direction of the ball's final velocity (toward the net) to be the +x-direction.)

(a) What is the impulse delivered to the ball by the racket?

magnitude ___ N · s

(b) What work does the racket do on the ball? (Indicate the direction with the sign of your answer.)

 ___J

A soccer player takes a corner kick, lofting a stationary ball 30.0° above the horizon at 23.0 m/s. If the soccer ball has a mass of 0.425 kg and the player's foot is in contact with it for 3.90 ✕ 10⁻² s, find the x- and y-components of the soccer ball's change in momentum and the magnitude of the average force exerted by the player's foot on the ball.

(a)the x- and y-components of the soccer ball's change in momentum (in kg · m/s)

Δp_x= ___kg · m/s

Δp_y= ___kg · m/s

(b) the magnitude of the average force exerted by the player's foot on the ball (in N)

 __N