Two horizontal forces, P and Q , are acting on a block that is placed on a table

Question

Two horizontal forces, P and Q , are acting on a block that is placed on a table. We know that P is directed to the left but the direction of Q is unknown; it could either be directed to the right or to the left. The object moves along the x-axis. Assume there is no friction between the object and the table. Here P = ?9.1 N and the mass of the block is 3.7 kg. (a) What is the magnitude and direction of Q when the block moves with constant velocity? (Indicate the direction with the sign of your answer.) What is the acceleration of an object if it moves with constant velocity? N (b) What is the magnitude and direction of Q when the acceleration of the block is +7.9 m/s2. (Indicate the direction with the sign of your answer.) N (c) Find the magnitude and direction of Q when the acceleration of the block is ?7.9 m/s2. (Indicate the direction with the sign of your answer.) N

Explanation / Answer

a) no acceleration,, Q will be just opposite of P Q= +9.1 N b)now Q> P b) Q=P+m*a Q=9.1+3.7*7.9=+38.33 c) first case,direction of Q is opposite of P Q= P-m*a Q=-20.13 .. invalid as we took it positive in assumption second case.. Q same direction as p Q=-(m*a-P) Q=- 20.13 N

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