A 4 kg object is moving at a speed of 5 m/s. The constant force needed to stop the object in 5 × 10-4 s will be:
1
+4×10+4 N in the direction of motion.
2
+20 N in the direction of motion.
3
+100 N in the opposite direction of motion.
4
+4×104 N in the opposite direction of motion.