An object of mass 0.61 kg is initially at rest. When a force acts on it for 2.9 ms it acquires a speed of 14.8 m/s. Find the magnitude (in N) of the average force acting on the object during the 2.9 ms time interval. (Enter a number.) N

B You have two identical books, A and B, each of mass m, on the palm of your hand as shown above. You move your hand upwards with the books, increasing the speed as time goes on. Which of the following is true? = A FH and on A = FHand on A FHand on A = FA on B+mg FHand on A > FB on A + mg FHand on A = 2mg FA on B FH and on B

Force F = (10N) sin (2πt/4.0s) (where t in s) is exerted on a 490 g particle during the interval 0 s≤ t ≤ 2.0 s. Part A If the particle starts from rest, what is its speed at t = 2.0 s? Express your answer to two significant figures and include the appropriate units. V = μA Value m S ?

A block with weight 50 N stops on an inclined plane which has angle 0 = 30° to the horizontal. Two observers try to analyse the forces on the block with their preferred reference. Observer A uses coordinate (xẠ, YA) as his reference while observer B uses coordinate (Xg, Yg) as her reference(See figure 1). YA Observer A Block Observer B XA W XB Figure 1. (a) Decompose the weight, W and the normal force, Ñ in the coordinate system of observer A. (b) Decompose the weight, W and the normal force, Ñ in the coordinate system of observer B. (c) Determine the magnitude of friction obtained by A and B respectively if the block tends to slide down. (d) Are the two answers in part (c) same or different? What does the result imply?