5.2 A pebble of mass 0.05 kg is thrown vertically upwards. Give the direction and magnitude of the net force on the pebble,

(a) During its upward motion

 

(b) During its downward motion

 

(c) At the highest point where it is momentarily at rest. Do your answers change if the pebble was thrown at an angle of 45° with the horizontal direction?

(Ignore air resistance.)

<p><strong> (a)</strong> During the upward motion f the pebble, the acceleration due to gravity acts downwards. The magnitude of the force is</p><p>F = MA = 0.05 kg&nbsp;<span title="Click to copy mathml"><math><mo>*</mo></math></span> 10 m/s² = 0.5 N and the direction of force is downwards.</p><p><strong> (b)</strong> During its downward motion – the force is 0.5 N and the direction is downwards.</p><p><strong> (c)</strong> When the pebble is thrown at an angle of 45 <span title="Click to copy mathml"><math><mo>°</mo></math></span>&nbsp;with the horizontal direction, it will have both horizontal component of force and vertical component of force during its upward journey, When it reaches the maximum height, the vertical component of velocity will becomes zero and the force acting will be 0.5 N and acting downwards.</p>

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