# Worksheet: Forces and Newton's Second Law of Motion

In this worksheet, we will practice identifying Newton's second law of motion as the relationship between an object's mass and its resultant acceleration when a force is applied to it.

Q1:

A sports car of mass 1,500 kg accelerates from 0 m/s to 30 m/s in a time of 10 s. What average force is exerted on the car during this acceleration?

• A N
• B N
• C N
• D N
• E N

Q2:

A car with a mass of 1‎ ‎000 kg applies brakes when it is moving at 90.0 km/h, and the car comes to rest after travelling 40.0 m. What is the net force on the car during its deceleration?

Q3:

Find the magnitude of the net force required to bring a car to rest if the mass of the car is 1,050 kg, its initial speed is 40.0 km/h, and its stopping distance is 25.0 m.

Q4:

A cart with a mass of 18 kg is at rest on a level floor. A constant 15-N force is applied to the cart at an angle below the horizontal. If friction is negligible, what is the speed of the cart when the force is applied over a distance 6.7 m?

Q5:

A baseball catcher is performing a stunt for a television commercial. He will catch a baseball (mass 145 g) dropped from a height of 60.0 m above his glove. His glove stops the ball in 0.0100 s. What is the force exerted by his glove on the ball?

Q6:

A baby dolphin of mass 35.0 kg decelerates from a horizontal speed of 12.0 m/s to a horizontal speed of 7.50 m/s, taking 2.30 s. What average force is exerted to slow the dolphin?

Q7:

The rocket sled shown in the accompanying diagram has a mass of kg. The sled decelerates at a rate of 196 m/s2. What force is necessary to produce this deceleration? Assume that the rockets have finished firing when the deceleration begins.

Q8:

A particle of mass 2.0 kg is initially at rest is acted upon by a single force for a time interval of 5.0 s.

What is the particle’s acceleration?

• A m/s2
• B m/s2
• C m/s2
• D m/s2
• E m/s2

What is the magnitude of the displacement of the particle at the end of the interval during which it is accelerated?

Q9:

A cleaner pushes a laundry cart of mass 6.30 kg. The cleaner pushes with a net external force of 53.4 N. Calculate the magnitude of the cart’s acceleration.

Q10:

What force does a trampoline have to apply to a 48.6-kg gymnast, to accelerate her vertically upward at 6.43 m/s2?

Q11:

A sprinter with a mass of 57.0 kg accelerates at 3.922 m/s2. What is the magnitude of the net external force on her?

Q12:

What is Newton’s second law of motion also known as?

• Athe law of action-reaction
• Bthe law of force
• Cthe law of gravitational attraction
• Dthe law of conservation of energy
• Ethe law of inertia

Q13:

A model helicopter of mass 1.50 kg has a velocity m/s at the instant . The helicopter is uniformly accelerated for 2.00 s. At the end of that interval, it has a velocity of m/s.

What magnitude average force acted on the helicopter between and ?

At what counterclockwise angle from the positive -direction was the force on the helicopter applied?

Q14:

A farmer is lifting some moderately heavy rocks from a field to plant crops. He lifts a stone that weighs 180 N. What magnitude force does the farmer apply if the stone accelerates at a rate of 1.50 m/s2?

Q15:

Find the mass of a car that is given an acceleration of m/s2 by a force of N.

Q16:

A particle of mass 4.0 kg is acted upon by four forces of magnitudes , , , and . acts at an angle of above the positive -direction, acts in the negative -direction, acts in the negative -direction, and acts in the positive -direction.

What is the particle’s acceleration vector?

• A m/s2
• B m/s2
• C m/s2
• D m/s2
• E m/s2

What is the magnitude of the particle’s acceleration?

At what angle below the positive -direction is the particle’s acceleration directed?

Q17:

A soccer ball of mass 0.400 kg is kicked across a field by a player and is given the acceleration .

State the force vector for the applied force on the ball.

• A N
• B N
• C N
• D N
• E N

What magnitude force was applied to the ball?

At what angle above the horizontal was the force applied?

Q18:

A cruise ship has a mass of kg. What acceleration of the ship is produced by applying to it a force of 6 MN?

Q19:

Two blocks are at rest and in contact with each other, resting on a frictionless surface, as shown in the diagram. The masses of the blocks are and respectively. A force of 24 N is applied to the smaller block. The blocks accelerate as a single system.

What is the magnitude of the system of blocks’ acceleration?

What magnitude force would be required to accelerate only the 6.0 kg mass block as much as the 24 N force accelerates the system of blocks?

Q20:

Two children pull a third child on a snow saucer sled exerting forces and as shown in the diagram. Find the acceleration of the 49.00 kg sled-and-child system. Note that the direction of the frictional force is unspecified; it will be in the opposite direction of the sum of and .

• A0.261 m/s2   north of east
• B0.152 m/s2   north of east
• C0.103 m/s2   north of east
• D0.139 m/s2   north of east
• E0.187 m/s2   north of east