Physical science Exam Preparation
The specific heat of ice is 2.1 kJ/kg°C. When 50 kJ of heat is removed from 2 kg of ice initially at -5°C, the final temperature of the ice is
-17°C.
A total of 4900 J is expended in lifting a 50-kg mass. The mass is raised to a height of
10 m.
A car starts from a speed of 10 m/s with an acceleration of 2 m/s2. The time needed for the car to reach 30 m/s is
10 s.
An airplane reaches its takeoff speed of 60 m/s in 30 s starting from rest. The time it spends in going from 40 m/s to 60 m/s is
10 s.
Fifty kJ of heat is added to a 10-kg piece of lead at its melting point of 330°C and 2 kg of lead melts. The heat of fusion of lead is
25 kJ/kg.
The primary coil of a transformer has 200 turns and its secondary coil has 50 turns, and the current in the secondary coil is 40 A. When a 12-V alternating current is applied to the primary coil of the transformer, the secondary voltage will be
3 V.
When its brakes are applied, a car moving at 10 m/s undergoes an acceleration of -1.2 m/s2. How far does the car travel before it comes to a stop?
42 m
chapter 2: A ball thrown upward at 30 m/s will reach the ground after about
6.0 s.
An electric iron draws a current of 15 A when connected to a 120-V power source. Its resistance is
8 ohms.
When a 430-g soccer ball is kicked, the impact lasts for 0.04 s. In order for the ball to fly off at 8 m/s, the force of the kick must be
86 N.
The speed of an object moving in a circle is doubled. The centripetal force needed is
four times as much as before.
When a sound wave goes from air into water, the quantity that remains unchanged is its
frequency.
Of these substances, the one with the lowest specific heat is
gold.
The weight of an object is
greater at the poles than at the equator.
When a liquid becomes a vapor,
it must absorb heat.
A bullet is fired upward. As it rises,
its mass remains the same while its weight decreases.
The wider the wavepacket of a particle, the
more precisely its momentum can be determined.
Matter waves are
never associated with stationary particles.
The setting sun appears red because its light is
scattered.
chapter 6 electricity: If undisturbed, an electric current in a superconducting wire loop
will continue indefinitely.
