Energy & Chemistry

It is the capacity to do work or transfer heat.

• Thermodynamics

• Energy

• Work

• Heat

A bowler lifts a 5.4-kg (12-lb) bowling ball from ground level to a height of 1.6 m (5.2 ft) and then drops it. (a) What happens to the potential energy of the ball as it is raised?

• its potential energy relative to the ground is the same.

• its potential energy relative to the ground decreases.

• its potential energy relative to the ground increases.

• All of the above

A bowler lifts a 5.4-kg (12-lb) bowling ball from ground level to a height of 1.6 m (5.2 ft) and then drops it. What quantity of work, in J, is used to raise the ball?

Answer explanation

The ball has a mass of 5.4 kg and is lifted 1.6 m. To calculate the work performed to raise the ball, we use Equation 5.3 and for the force that is due to gravity:

w = F x d = m x g x d

= (5.4 kg)(9.8 m/s² )(1.6 m)

= 85 kg-m²/s²

= 85 J

A bowler lifts a 5.4-kg (12-lb) bowling ball from ground level to a height of 1.6 m (5.2 ft) and then drops it. After the ball is dropped, it gains kinetic energy. If all the work done in part (b) has been converted to kinetic energy by the time the ball strikes the ground, what is the ball’s speed just before it hits the ground? (Note: The force due to gravity is , where m is the mass of the object and g is the gravitational constant; g = 9.8 m/s²

A system loses 1150 J of heat to the surroundings. The piston moves downward as the gases react to form a solid. As the volume of the gas decreases under the constant pressure of the atmosphere, the surroundings do 480 J of work on the system. What is the change in the internal energy of the system?

• 670 J

• -670 J

• 1630 J

• -1630 J