Top

# Physics Problems

Physics Problems is an excellent online study resource for students. It is an exhaustive collection of solved examples and answers for physics problems and questions.

Students can get online tutors who can help them understand the concepts and the logic behind the answers for Physics Questions. They can also get help with their homework problems in physics and other assignment questions related to Physics. The online physics tutors are expert in their subjects who can help the students  in solving all their queries. One can also get physics homework help from our tutors.

Physics problems cover all the important topics under physics for various grades. The students can get grade-specific help with their physics problems. The students can learn by observing the solved examples. They can understand the concepts step by step, therefore, they would be able to solve physics problems on their own. They can even learn about the topics in depth and practice problems on physics which in turn will help them to prepare for their exams.

## Physics Problems and Solutions

Physics questions and answers is an entire list of solved problems and questions on physics. The students can get the list of frequently asked questions of various physics topics. The following are some physics topics which are covered under the physics problems:

• Fundamental operations
• Motion
• Forces
• Gravity
• Work, Energy and Power
• Momentum
• Thermodynamics
• Fluids
• Electricity and Magnetism
• Modern Physics

Students can also get help on other branches of science on the science help page.

## Physics Classroom Examples

Here are some physics classroom examples for students:

### Solved Examples

Question 1: A car moving with a velocity of 18 kmph is brought to rest in a distance of 0.5 km by applying brakes. Find its retardation?
Solution:

Initial Velocity of the car = u = 18 kmph = 5 ms-1,
Final Velocity of the car = v = 0,
Distance travelled = S = 0.5 km = 500m
We have, v2 = u2 + 2as.
0 = 52 + 2 $\times$ a $\times$ 500
= 25 + 1000a.
-25 = 1000a,
a = -0.025 ms-2.
$\therefore$ Retardation of the car = 0.025ms-2.

Question 2: A Heat engine operates with reservoir temperature between 900 K and 500 K. Calculate its efficiency?
Solution:

T1 = 900 K,
T2 = 500 K,
Efficiency $\eta$ = 1 - $\frac{T_{2}}{T_{1}}$
= 1 - $\frac{500}{900}$
= 0.46.
Hence the efficiency of the engine is 46%.

## How to Solve Physics Problems?

Students can learn how to solve physics problems based on the methodology followed and illustrated in the solved examples. They can even get physics problems solved online. They will also get the explanation for them from the expert tutors. The Sample problems for Motion, momentum, energy, Heat, thermodynamics have been covered.
The following are some solved examples from some topics under physics:

### Solved Examples

Question 1: A car travels at 30 kmph for 10 minute, 60 kmph for next 20 minute and 40 kmph for the next 30 minute. What will be the average speed of the car for the complete motion?
Solution:

Speed of the car for first 10 minute i.e., $\frac{1}{6}$ hour is u1 = 30 kmph.
Distance traveled in this time interval is S1 = u1 t1 = 30 $\times$ $\frac{1}{6}$
= 5 km.
Speed of the car for the next 20 minute i.e., $\frac{1}{3}$ hour is u2 = 60 kmph.
Distance traveled in this time interval is S2 = u2 t2 = 60 $\times$ $\frac{1}{3}$
= 20 km.
Speed of the car for the next 30 minute i.e., $\frac{1}{2}$ hour is u3 = 40 kmph
Distance traveled in this time interval is S3 = u3 t3 = 40 $\times$ $\frac{1}{2}$
= 20 km
Total distance traveled is given by S = S1 + S2 + S3

= u1t1 + u2t2 + u3t3
= 5 + 20 + 20
= 45km.
Total time taken is given by: t = t1 + t2 + t3 = $\frac{1}{6}$ + $\frac{1}{3}$ + $\frac{1}{2}$
= $\frac{1 + 2 + 3}{6}$ = 1hr
Average speed for the complete motion is,$\bar{v}$ = $\frac{s}{t}$
= $\frac{45}{1}$
= 45 kmph.

Question 2: A force of 100 N acting on a body for 5s acquires a velocity of 20ms-1. Find its
(i) Mass
(ii) Momentum of the body at the end of 1s?
Solution:

Given:
F = 100 N,
t = 5 s,
u = 0,
v = 20 ms-1, Let a be the acceleration.
Then v = u + at
Acceleration(a) = $\frac{v-u}{t}$
= $\frac{(20 - 0) ms^{-1}}{5 s}$
= 4 ms-2.
Mass(m) = $\frac{F}{a}$
= $\frac{100 N}{4 ms^{-2}}$
= 25kg.
At the end of 5s, v = 20 ms-1
$\therefore$ Momentum p = mv
= 25kg $\times$ 20 ms-1
= 500 kg ms-1.

Question 3: Find the Heat given out per unit area in 1 hour by a furnace whose temperature is 2000K?
Assume $\sigma$ = 5.7 $\times$ 10-8 W m-2 k-4.
Solution:

Energy radiated per second per unit area = $\sigma$ T4
$\therefore$ E = $\sigma$ T4 t
T = 2000 K,
t = 3600s
E = 5.7 $\times$ 10-8 $\times$ (2000)4 $\times$ 3600
= 0.33 $\times 10^{10}$ J.

## School Physics Problems

We are providing Solved Problems as well as Practice Problems for both lower grade and higher grade students which will help them solve problems at school easily.
Some problems are given below:

### Solved Examples

Question 1: A vehicle covers a distance of 60 m in 20 seconds. Calculate the Vehicle's speed?
Solution:

According to the formula of speed,
We know that Speed = $\frac{Distance}{time}$
= $\frac{60}{20}$
= 3 m/s.

Question 2: If an electrical lamp lights for 2 hours drawing current of 0.4 A. Calculate the amount of charge that passed through the lamp?
Solution:

Given: Current, I = 0.4 A,
Time, t = 2hours
t = 2 $\times$ 60 $\times$ 60 = 7200 seconds
Q = ?
Amount of charge, Q = It
= 0.4 $\times$ 7200
= 2.88 $\times$ 103 C.

## Physics Practice Problems

We are also providing the Practice Problems for the students to improve their skills and ability to check their intellectual level. This will help them to speed up their potential and also to do good in their tests.
Some practice problems along with their solutions are given below:

### Solved Examples

Question 1: Obtain the acceleration due to gravity on the surface of the earth.
Given Radius of earth R = 6.37 $\times$ 103 km,
Mass of earth M = 5.98 $\times$ 1024 kg,
Gravitational constant G = 6.67300 $\times$ 10-11 m3 kg-1 s-2

Solution:

Equation of force,
F = $\frac{GMm}{R^{2}}$
Where F is the force,
m is the mass of the body,
g is the acceleration due to gravity,
M is the mass of the Earth,
R is the radius of the Earth and
G is the gravitational constant
F = $\frac{GMm}{r^{2}}$ = m $\times$ a.
The acceleration due to gravity is given by
a = $\frac{GM}{r^{2}}$
= $\frac{6.67300 × 10^{-11} m^{3} kg^{-1} s^{-2} \times 5.98 \times 10^{24} kg}{6.37 \times 10^{3} m}^{2}$.
= 9.8 m/s2.

Question 2: An electric Heater is connected to a 220 V mains supply and draws a current of 5 A. Calculate the Power rating of the Heater?
Solution:

Current drawn I = 5 A
$\therefore$ Power rating P = V $\times$ I
= 220 $\times$ 5
= 1100 W.
Thus the Power rating is 1100 W.

*AP and SAT are registered trademarks of the College Board.