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Class 10 Class 12

An explosion blows a rock into three parts. Two parts go off at right angles to each other. These two are 1 kg first part moving with a velocity of 12 ms-1 and 2 kg second part moving with a velocity of 8 ms-1.If the third part flies off with a velocity of 4 ms-,its mass would be

• 5 kg

• 7 kg

• 17 kg

• 3 kg

A.

5 kg

apply the law of conservation of linear momentum.

momentum of first part = 1 x 12 = 12 kg ms-1
Momentum of the second part  = 2 x 8 = 16 kg ms-1 '

Resultant monmentum

= [(12)2 +(16)2]1/2 = 20 kg ms-1

The third part should also have the same momentum.

Let the mass of third part be M, then

4 x M = 20

M = 5 kg

apply the law of conservation of linear momentum.

momentum of first part = 1 x 12 = 12 kg ms-1
Momentum of the second part  = 2 x 8 = 16 kg ms-1 '

Resultant monmentum

= [(12)2 +(16)2]1/2 = 20 kg ms-1

The third part should also have the same momentum.

Let the mass of third part be M, then

4 x M = 20

M = 5 kg
3233 Views

Is Aristotle’s law of motion now correct?

No. Aristotl'e law of motion is false.
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What is Aristotle’s law of motion?

Aristotle’s law of motion states that an external force is required to keep the body in motion.
2445 Views

Define inertia.

The property by virtue of which the body cannot change its state of rest or uniform motion in a straight line, unless an external force is acting on the body is called as Inertia.
1316 Views

State Galileo’s law of motion.

Galileo’s law of motion states that, a body continues to move in the same direction with constant speed, if no force is acting on the body.
1332 Views

When the branches of an apple tree are shaken, the apples fall down. Why?

The apple fall from an apple tree when it shaken because of inertia of rest. Apple is in a state of rest and when the tree is suddenly shaken, apples still tends to remain in it's same state of rest whereas branches move.

So, the apples fall down.
1475 Views