Question

Please Solve the given word problems by following GRESA.

1. A net force of 15 N acts on a box which has a mass of 3 kg. What will be the acceleration of the box?

2. How much horizontal net force is required to accelerate a 1000 kg car at 4 m/s2?

3. A 0.15 kg rubber ball is attached to 1.3 m string. The ball swung in a horizontal circle on a friction less table, making one revolution in 1.18 s. With what speed is the ball traveling?

4. A 1.5 kg ball on a string is rotated about a circle of radius 10 m. The velocity is 15.34 m/s at the bottom.

Find and answer/solve all the following:

a. acceleration

b. net force

c. gravitational force

d. tension force

Answer 1

1) Determine the acceleration:

$$a=F/m=15/3=5\text{ m/s}^2.$$

2) The force is

$$F=ma=1000·4=4000\text{ N}.$$

3) The speed:

$$v=\frac LT=\frac{2\pi r}{T}=\frac{2\pi·1.3}{1.18}=6.92\text{ m/s}.$$

4a) Acceleration:

$$a_c=\frac {v^2}{R}=23.53\text{ m/s}^2.$$

4b) Net force:

$$F_\text{net}=F_c+F_g=m(a_c+g)=50\text{ N}.$$

4c) Gravitational force:

$$F_g=mg=14.7\text{ N}.$$

4d) Tension:

$$T=F_\text{net}=50\text{ N}.$$