A wooden block with mass 1.50 kg is placed against a compressed spring at the bottom of an incline of slope 30.0o (point A). When the spring is released, it projects the block up the incline. At point B, a distance of 6.00 m up the incline from A , the block is moving up the incline at 7.00 m/s and is no longer in contact with the spring. The coefficient of kinetic friction between the block and the incline is µk = 0.50. The mass of the spring is negligible. Calculate the amount of potential energy that was initially stored in the spring.
Solution 81P Step 1: Data given Mass of the block m = 1.5 kg Velocity up the plane v = 7 m/s 0 Angle of inclination = 30 Coefficient of kinetic friction k = 0.50 We need to find the force exerted on the spring by the block It is given by F = mg k Substituting values we get F = 0.50 × 1.5 kg × 9.8 F = 7.35 N Hence the force on the spring is 7.35 N