Dynamics and Energy Practice Quiz

Answer explanation

Using Newton's second law, F = ma, we can find acceleration (a) by rearranging the formula: a = F/m. Here, a = 25 N / 5 kg = 5 m/s². Thus, the resulting acceleration is 5 m/s².

Mathematical Equivalence

ON

The masses of four objects are given in this table. If all objects are struck with a force of 10 Newtons, which one will have the greatest acceleration? (F = ma)

• Object 1

• Object 2

• Object 3

• Object 4

Answer explanation

According to F = ma, acceleration (a) is inversely proportional to mass (m). The object with the least mass will experience the greatest acceleration when the same force is applied. Therefore, Object 4, having the least mass, has the greatest acceleration.

Answer explanation

Using Newton's second law, F = ma, we can find acceleration (a) by rearranging the formula: a = F/m. Here, F = 20 N and m = 4 kg. Thus, a = 20 N / 4 kg = 5 m/s². Therefore, the correct answer is 5 m/s².

Answer explanation

Momentum is calculated using the formula \( p = m \cdot v \). Here, \( m = 2 \, \text{kg} \) and \( v = 5 \, \text{m/s} \). Thus, \( p = 2 \, \text{kg} \times 5 \, \text{m/s} = 10 \, \text{kg m/s} \). The correct answer is \( 10 \, \text{kg m/s} \).

Determine the momentum of 1000-kg car moving southward at 20 m/s......... 

• 20000 N

• 20000 Joules

• 20000 Kg * m/s south

• 10000 kg * m/s south

Answer explanation

Momentum is calculated as mass times velocity. For a 1000-kg car moving at 20 m/s south, momentum = 1000 kg * 20 m/s = 20000 kg*m/s south. Thus, the correct answer is 20000 Kg * m/s south.

A runner has a momentum of 720 kg m/s and is traveling at a velocity of 5 m/s. What is his mass?

• 14.4 kg

• 1400 kg

• 144 kg

• 360 kg

Answer explanation

Momentum (p) is calculated as mass (m) times velocity (v): p = m * v. Rearranging gives m = p / v. Here, m = 720 kg m/s / 5 m/s = 144 kg. Thus, the runner's mass is 144 kg.

A 10 N force is causing a 2 m/s squared acceleration on an object. What is the mass of the object? (m = F/a)

• 3 kg

• 12 kg

• 5 kg

• -5 kg

Answer explanation

Using the formula m = F/a, we can calculate the mass. Here, F = 10 N and a = 2 m/s². Thus, m = 10 N / 2 m/s² = 5 kg. Therefore, the mass of the object is 5 kg.

Answer explanation

The potential energy (PE) is calculated using the formula PE = mgh. Here, m = 50 kg, g = 9.8 m/s², and h = 30 m. Thus, PE = 50 * 9.8 * 30 = 14700 J. Therefore, the correct answer is 14700 J.

A 0.250 kg cart moving at 0.400 m/s has how much momentum?

• 0.1 kg-m/s

• 1 kg-m/s

• 10 kg-m/s

• 100 kg-m/s

Answer explanation

Momentum is calculated using the formula p = mv, where p is momentum, m is mass, and v is velocity. Here, p = 0.250 kg * 0.400 m/s = 0.1 kg-m/s. Thus, the correct answer is 0.1 kg-m/s.