NIOS Class 10 Science Force and Motion Worksheet 10 Answers | Complete Solution

This worksheet 10 contains questions based on Force and Motion with complete solution.

This post explains the answers of questions given in the worksheet including explanation, diagrams. These solutions will help you complete your assignments and TMA also.

Force and Motion Worksheet 10 Questions- Answers

Q1. Though a force is not visible; its effect can be seen or experienced. Observe your surroundings and mention different kind of effects of force on different objects.

Answer

Force cannot be seen but we can feel its effects in our surroundings in many ways.

Following are the effects of force on different objects-

1. Force can move a stationary object – When we kick a football, it starts moving.

2. Force can stop a moving object – When we apply brakes on bicycle, it stops.

3. Force can change the direction of moving object- A cricket player changes the direction of cricket ball by hitting it.

4. Force can change the shape of an object- When we press a rubber ball, its shape is changed.

5. Force can change the speed of an object- Pushing a swing makes it move faster.

So, these are some examples of effects of force on different objects.

Q2. Write an activity for understanding the concept of balanced and unbalanced forces. Based on observation of above activity, differentiate between balanced and unbalanced forces.

Answer

Activity – To understand the concept of balanced and unbalanced forces

Materials Required

1. Strong rope

2. Two teams of equal number of students

Procedure

1. Mark a line on the ground between the two teams

2. Ask both teams to hold the rope from opposite ends

3. When both teams pull the rope with equal force and observe the position of the rope.

4. Now aske the one team to pull harder and observe the position of rope.

difference between balanced and unbalanced forces.

Observation

When both teams pull with equal force, the rope remains at the same position.

When one team pulls with greater force than the other team pulls, the rope moves towards the first team (pull with greater force)

Explanation

When the force applied by both teams are equal and opposite, they balance each other, this is called a balanced force.

When one team applies greater force, the force becomes unbalanced and rope moves.

Difference between balanced and unbalanced force

Balanced forces	Unbalanced forces
Equal in magnitude and opposite in direction	Unequal in magnitude and not opposite in direction
Do not change the state of rest or motion	Change the state of rest or motion

Conclusion

Through this activity, we can easily understand balanced and unbalanced forces and differentiate between them.

Q3. There are three solids made of different materials such as fibre, plastic and wood having the same shape and same volume. Which of them would have highest inertia and why?

Answer

Inertia: - The tendency of an object to resist any change its state of rest or motion. The inertia of an object depends on the mass of the object.

So, the object with greater mass has the greater inertia.

We have three solids made of fibre, plastic and wood of the same shape and volume. Wood has the highest mass among three so it has highest inertia.

Q4. While traveling in a train keep three balls of the same size but of different materials, i.e. marble, rubber and iron on the smooth floor of moving train. The brakes are applied suddenly to stop the train. Observe, will the ball start rolling or will stay at same position? If the balls start rolling, in which direction it will move? Support your answer with suitable reasons.

Answer

When the brakes are applied suddenly, all the three balls of marble, rubber and iron start rolling forward (the direction in which the train was moving).

The three balls are also moving with the same speed on which the train is moving. When brakes are applied, the train stopped but the balls keep moving forward due to inertia of motion.

The iron ball is heaviest in among the three and it has greatest inertia so it will roll farthest.

Q5. Why a fielder in a game of cricket pulls his hand backwards after catching a fast-moving cricket ball? It’s an example of second law of motion. In our everyday life we see many applications of second law of motion. Observe your surroundings and give examples of applications of second law of motion in day-to-day life.

Answer

When a fielder catches a fast-moving cricket ball, he pulls his hands backward to increase the time taken to stop the ball because in this time the momentum of ball becomes zero.

So, the rate of change of momentum decreases and the force acting on his hands becomes less, so he feels less pain.

Examples of Newton’s Second Law of Motion in daily life

1. Kicking a football

2. Pushing a shopping cart

3. Driving a car

4. Throwing a stone

5. Launching of rocket

Q6. Using second law of motion, derive the relation between force and acceleration. A bullet of 10g hits an object with the speed of 130 ms^-1 and gets embedded after travelling 5 cm. Calculate –

(i)The resistive force exerted by the sand on the bullet

(ii) Time taken by the bullet to come to rest

Answer

Derivation of relation between force and acceleration

According the Newton’s second law of motion “ the rate of change of momentum of an object is directly proportional to the applied force and takes place in the direction of force.

Mass of body =m

Initial velocity =u

Final velocity =v

According to the second law

We know

( k is constant)

If k =1

Then

This the relation between force and acceleration

Numeral Solution

Given values

Mass of bullet (m)= 10 g= 0.01kg

Initial speed (u) = 130m/s

Final speed (v) = 0m/s

Distance travelled while stopping (s) = 5cm =0.05m

Force (F) =?

Time (t) =?

(i) Find force

We know

F=ma

We have to find acceleration (a)

0 = (130)² + 2a (0.05)

m/s²

The negative sign show acceleration is opposite in the motion.

Now we put the value of acceleration in the formula

F=ma

F = 0.01 × (-169000)

F= 1690N

(ii) Time take to come to rest

0= 130+ (-169000)t

Q7. A book exerts a force of 2N downwards, into a chair that exerts a force of 5N downwards to the floor it stands on. What is the force that the floor exerts upwards on the chair? Also describe the phenomenon of a seat belt keeping someone restrained in their seat during a car crash. In other words, why did the person not leave their seat?

Answer

(A) Force exerted by the floor

Given values

Force exerted by book on chair = 2N

Force exerted by chair on floor = 5N

Solution

Total downward force on the floor = 2N + 5N= 7N

According to the Newton’s third law of motion –“ For every action, there is an equal and opposite reaction”

So, the floor exerts an equal and opposite upward force of 7N on the chair

(B) When a car is moving , both the car and the person inside are moving at the same speed in the same direction.

If car stops suddenly (like in crash), the person’s body tends to moving forward because of inertia of motion according Newton’s first law of motion.

The seat belt applies an opposite force on the person and stop him to move forward and prevents him to be injured.

Q8. Two cars, one of mass 500 kg and another of mass 250 kg, collide head on. Describe which car will experience more force and more acceleration with respect to the other car and why?

Answer

(A) Force experienced by cars

Both cars will experience an equal magnitude of force during the collision. According to Newton’s third law of motion- For every action, there is an equal and opposite reaction.

(B) Acceleration experienced by cars

250 kg car will experience more acceleration because it has less mass, according to the Newton’s second law of motion

F=ma

So, for the same force, the car with smaller mass will experience more acceleration.

Q9. First law of motion or law of inertia states that “an object continuous to be in a state of rest or of uniform motion in a straight line unless it is acted upon by a ne external force.” Now roll a ball along the ground and observe its motion. Explain why ball comes to rest after travelling some distance without any external force acted upon it.

Answer

According to Newton’s First law of motion- An object always remains in state of rest or motion unless it experiences an external force.

However, we roll a ball on the ground, it gradually slows down and stops after travelling some distance.

This happens because external forces like – friction and air resistance act on the ball. These forces oppose the motion of the ball and reduce its speed.

Q10. Observe your surroundings and give two examples of friction that are useful and two examples of friction that are not useful. In case of useful how you will increase friction? In case of not useful, write the method to reduce friction

Answer

(1) Useful friction

Friction is helpful in many daily activities.

i. Walking on the ground – When we walk, friction between our shoes and the ground help us walk without slipping.

ii. Brakes in vehicle – Friction between brake pads and wheels helps to stop the vehicle.

Increase useful friction

We can increase useful friction by making surface rough and using materials that increase grip like rubber mats.

(2) Not useful friction (harmful friction)

Some friction cause problems and energy loss that waste out time and money.

i. Friction in machine parts produces heat and wears them out.

ii. Friction between moving parts in a fan or engine reduces efficiency.

Reduce harmful friction