Question

A boat leaves a harbor at 30 km/h toward the south. is there a net force present A bicycle goes around a curve at a constant speed of 8 m/s...is there a net force present A hockey puck slowly comes to a stop after being struck at 90 ft/s on an icy rink...is there a net force present A sprinter takes off from rest and reaches a speed of 20 mi/h...is there a net force present

Answer 1

1.As boat is moving with constant velocity 30 km/h and it's direction does not changing (moving to south ) hence there is no net force acting on the boat.

2. Speed of bicycle is v= 8 m/s which is constant however the direction of velocity is changing on every point on curve hence there will be acceleration which is given by v^2/r .r = radius of curve .Hence there exist a force on the bicycle

3.As there exist change in velocity 90 ft/s to 0 ft/s hence there will be acceleration (negative) . Hence there will be a force on the on puck.

4.As velocity of sprinter change from 0 mi/h to 20 mi/h . So there will be acceleration . Hence there will be force on the sprinter.