Test: Force - Class 9

Force is a push or a pull that changes or tends to change the state of rest or uniform motion of an object or changes the direction or shape of an object

Option C is correct.

The correct option is A

is to note any change in the objects state of motion.

One way that you can recognize that a force is acting on an object is to note any change in the objects state of motion.

The correct option is A

The object will accelerate in the direction of the applied force.

The object will accelerate in the direction of the applied force.

If an object experiences a net zero unbalanced force, then the body moves with a constant velocity, or if it was at rest, then it continues to remain at rest.

Option D is correct.

The correct option is A

A person resting on an armchair.

A person in the armchair is at rest, not moving. Hence, the forces are balanced

Here, m = 1kg, u = 20 ms^-1, v = 0, s = 50m, F = ?

From v² - u² = 2as

0 - (20)² = 2a x 50 = 100a

a = -400/100

a = -4 ms^-2

∴ F = ma

F = 1 (-4)

F = -4 N

Negative sign indicates that force of friction is opposing the motion of the ball.

Friction is a a force that comes into play when two surfaces come in contact with each other. The frictional force acts in the opposite direction of the motion of the object. The force of friction opposes the relative motion between the surfaces of two moving objects.

Option D is correct.

There is no unbalanced force. There might be a number of forces acting on the body but these forces are adding up to zero.

Option B is correct.

1.for state - if we exert high force on ice it slowly start converting into water I.e liquid thus state is change by force. 

2.for position - if we push a box it change its position. thus force also change position. 

3. for shape - if we press a clay it will change its shape so we can conclude that force change shape also. 

Therefore Option D is correct.

Kg ms^-2 is also called Newton as unit of force is newton.

Option D is correct.