Newton's Laws Of Motion Test

Result

Newton's Laws Of Motion Test - 8

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

Ten coins are placed on top of each other on a horizontal table. If the mass of each coin is 10 g and acceleration due to gravity is 10 ms^–2, what is the magnitude and direction of the force on the 7^th coin (counted from the bottom) due to all the coins above it?

A
0.3 N downwards

B
0.3 N upwards

C
0.7 N downwards

D
0.7 N upwards

Solution

Mass of each coin (m) = 10 g = 0.01 kg.

The 7^th coin from the bottom has 3 coins above it.

Hence, the force on the 7^th coin = weight of 3 coins = 3 mg = 3 × 0.01 × 10 = 0.3 N, vertically downwards.

Thus, the correct choice is (1).
Question 2
1 / -0

Directions: In the following question, Statement-1 (Assertion) is followed by Statement-2 (Reason). There are four choices given below the statements, out of which only one choice is correct.

Statement-1: When a ball dropped from a certain height hits the floor, it exerts a force equal in magnitude to its rate of change of momentum.

Statement-2: The floor does not move because the action and reaction forces, being equal and opposite, cancel each other.

A
Statement-1 is true, Statement-2 is true and Statement-2 is the correct explanation for Statement-1.

B
Statement-1 is true, Statement-2 is true, but Statement-2 is not the correct explanation for Statement-1.

C
Statement-1 is true; Statement-2 is false.

D
Statement-1 is false; Statement-2 is true.

Solution

The assertion is true, but the reason is not correct because action and reaction forces do not act on the same body and hence, do not cancel each other. Hence, the correct choice is (3).